The Peter Attia Drive - #198 - Eye health—everything you need to know ｜ Steven Dell, M.D.

00:00:00.000 Hey, everyone. Welcome to the drive podcast. I'm your host, Peter Atiyah. This podcast,

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00:00:41.720 head over to peteratiyahmd.com forward slash subscribe. Now, without further delay,

00:00:47.740 here's today's episode. I guess this week is Steven Dell. Steven is an internationally recognized

00:00:54.980 leader in refractive eye surgery, specializing in LASIK surgery, cataract surgery, and refractive

00:01:01.540 lens exchange. He's also the chief medical editor of the journal Cataracts and Refractive Surgery

00:01:06.820 Today. He's the emeritus chair and president emeritus of the American European Congress of

00:01:13.380 Ophthalmologic Surgery. He's a principal investigator on a variety of FDA clinical trials in the field of

00:01:18.360 eye surgery. He is the inventor of several surgical instruments and devices and holds over 20 US and

00:01:24.640 international patents in the field of eye surgery. He is also the author of numerous textbook chapters

00:01:29.260 and peer-reviewed journal articles. In this episode, we talk about all things related to the eye. And I'm

00:01:34.800 pretty open in the outside of this and explaining that of all the things that one would learn in

00:01:41.240 medical school, there are none that I know less about than the eye. In fact, I come into this episode

00:01:46.360 truly knowing as little as a lay person would know about the eye. And I think at the outset of the

00:01:52.360 interview, I explained the extent to what I know about the eye. And while it may be slightly more

00:01:57.000 than you will know, I promise you that within about 15 minutes of this episode, we are all going to be

00:02:02.220 at the same level. So this for me was just a fascinating discussion. And I treated it almost like

00:02:08.240 the discussion I would have with Steven if we were at a cocktail party, really picking his brain about

00:02:13.460 kind of the anatomy of the eye, why it's relevant, how it factors into the natural processes of aging,

00:02:18.660 and how those kind of differ from some of the pathologic processes that also tend to increase

00:02:24.060 with aging but are not necessarily related to aging per se. We get into just the really simple

00:02:29.900 fundamentals of what is nearsightedness, what is farsightedness, what is presbyopia, which by the way,

00:02:35.340 I used to think was farsightedness until I did this interview. We talk, of course, about what the

00:02:39.920 treatments look like for these things and basically get into a very nuanced discussion about how the

00:02:46.700 different treatments might be beneficial to some people versus others. So we talk obviously about

00:02:51.840 LASIK eye surgery, but we also talk about a procedure that came along slightly before that

00:02:55.780 called PRK. We talk a little bit about a procedure that is just coming online today called SMILE.

00:03:00.700 All three of these are similar, but they differ in fundamental ways. And that can be an important

00:03:05.640 thing to consider if you are in the market for one of these procedures. We also talk about eye

00:03:10.400 health. What are the things that we can do? And for many of us listening to this, it's what can we do

00:03:14.860 for our kids to maximize eye health? We talk about some of the real epidemics that are going on in

00:03:20.460 myopia. That is to say, kids that are requiring glasses earlier and earlier, what that might be about

00:03:26.160 and what we can do in our kids to prevent those things and also in ourselves, what we can be doing.

00:03:31.360 So anyway, there's a lot of stuff that's covered in here. This is really kind of the everything

00:03:35.240 you need to know about the eye episode. And I hope you enjoy it as much as I did.

00:03:39.720 So without further delay, please enjoy my conversation with Dr. Stephen Dell.

00:03:48.880 Hey, Stephen, thank you so much for coming over. As we were talking about, I don't really do many

00:03:52.880 of these in person anymore, often just out of sheer laziness, but I do enjoy it a lot more. So the fact

00:03:58.080 that I know it was a bit of a hassle, you had to probably change clinic or something today,

00:04:01.940 but anyway, really appreciate you coming out. And this is a topic that I think everybody has

00:04:07.000 questions on this topic and everybody, myself included, is comically ignorant on this topic.

00:04:13.920 I mentioned to you a few minutes ago, the extent of my knowledge from medical school. I remember

00:04:18.220 there's an optic nerve. I remember it's a cranial nerve. I think it's even the second cranial nerve.

00:04:24.100 There you go. You're ahead of the game.

00:04:25.860 I remember something called a fovea.

00:04:27.720 And I know there's a blind spot, but I've kind of forgotten why. So it's safe to say my knowledge

00:04:34.020 of this topic right now is probably at par with everybody's, right?

00:04:39.360 Well, that's not rare, frankly, because the eye is so literally compartmentalized.

00:04:44.380 We just don't interact that much with other specialties. So it's not rare for people who

00:04:50.520 are in other specialties to be very ignorant of the eyeball. And that's fine because I think it'll

00:04:55.340 help us keep the level of discussion at an approachable level for everyone.

00:05:00.260 Has there ever been a discussion about suggesting that ophthalmologists don't need to do the four-year

00:05:06.540 MD degree? Like how much of what you learned in medical school became relevant in your residency?

00:05:12.100 Actually, quite a lot, honestly.

00:05:14.340 Yeah, because you think about it, the eyeball, there's really nothing specifically magical about

00:05:18.660 the eyeball. It's got neurological tissue in the back, actual brain tissue in the back.

00:05:23.760 It's got a vascular supply. There are a lot of crossovers to other medical disciplines. All of

00:05:30.580 the cellular processes are the same. We operate adjacent to the eye. I think it's important for

00:05:37.600 us to have a general sense of medical knowledge, particularly because so many systemic diseases

00:05:43.280 manifest as eye problems. Now, there is a discipline of medical training or of visual training,

00:05:50.740 basically optometry, which deals with the eye, but not all of the surgical stuff. So we work in a

00:05:59.880 collaborative fashion with optometrists. And those are the folks who are fitting glasses. They're

00:06:06.340 screening for eye disease. They're handling preoperative and postoperative care. In many

00:06:10.780 cases, they're treating some diseases that are specific to the eye, like glaucoma, for example.

00:06:16.720 And we work in a collaborative fashion with them. Does everyone in an ophthalmology residency spend

00:06:23.940 time operating? There's no non-surgical discipline to this, right? It doesn't bifurcate in the training?

00:06:29.460 Well, it does, actually. There are non-surgical ophthalmologists, but I think they all start out

00:06:35.620 as surgeons. To become an ophthalmologist, you're really training to become an eye surgeon.

00:06:40.460 But there are, for example, neuro-ophthalmologists, which are really more neurologists than eye

00:06:48.340 surgeons. In fact, it's typical that they don't do eye surgery. So there are some ophthalmologists

00:06:54.880 who don't do eye surgery. One of my sort of lasting memories from residency was stealing suture from the

00:07:02.120 ophthalmology OR at Hopkins. Because I guess for people who don't know, the number of the suture,

00:07:08.660 of course, gets larger. The suture gets smaller. So an O suture is like you can see how thick it is.

00:07:15.380 It's like a piece of rope. 1-0, 2-0, 3-0. By the time you're at 4-0, it's actually quite thin.

00:07:20.860 Right. We use 11-0.

00:07:22.040 Exactly. In cardiac surgery, you're using a 7-0. Occasionally, there's some guys that would sew

00:07:27.760 the distal end of a coronary artery with an 8-0. And at that level, it's already very thin. I mean,

00:07:35.260 just the slightest tug too much and it breaks. But then in ophthalmology, you guys were at 11-0.

00:07:40.980 And so I used to steal 11-0 constantly. Every night I was on call and practice suturing with 11-0,

00:07:47.560 the thinking being if you can tie an 11-0 with your hands and not tear it, that 7-0, which normally

00:07:53.940 is like a piece of hair, is going to feel like a piece of rope. So I used it to help me develop a good

00:07:59.020 feel for fine suture. And then I also realized I'm kind of being a schmuck here. I bet this 11-0 0.98

00:08:05.620 stuff's really expensive. And I'm just stealing it like there's taking it to the call room all night.

00:08:10.200 More likely, it was probably 10-0. But yes, our tools are little tiny tools. And I can remember

00:08:16.100 our operating room when I was in training was sort of near the orthopedic surgery

00:08:20.860 area. And you hear this Black and Decker stuff going on over there. And our little tiny tools

00:08:27.520 are very, it's just totally different. Is everything you do under a microscope

00:08:31.480 operationally? Like you don't operate with a naked eye, right?

00:08:34.780 Right. It's all under a microscope. Just to put it in a visual for people who may not be familiar,

00:08:41.160 we have a binocular microscope. So I'm looking through both eyes. And this is either mounted

00:08:46.860 from the ceiling and is controlled by my feet. So the X, Y, and Z, and the zoom focus are controlled

00:08:54.180 by a foot pedal. And that either comes from the ceiling or it's on a really large stand.

00:08:59.540 So I'm sort of sitting, I'm looking straight ahead. So the image is here, but I'm operating down here.

00:09:07.520 And it's interesting because sometimes my wife will kid me, I'll come home from a day of surgery

00:09:12.780 exhausted. But she said, she says something like, well, I don't really get it. You're just

00:09:17.880 sitting in a chair, sort of making these little tiny movements and there's soft music playing.

00:09:25.560 It all seems very, very sedate. It's incredibly stressful and exhausting.

00:09:30.400 Although I will say in your wife's defense, she has it harder because of the kids.

00:09:34.040 Yeah, that's true. For sure. Let there be no misunderstanding about that. It's way easier.

00:09:39.820 Well, actually, I didn't realize, I never really thought about that. But the other advantage you

00:09:42.580 have is you don't have that cervical flexion problem that most surgeons have when they're

00:09:47.140 in an open. I mean, nowadays with more robotic and laparoscopic surgery, you can be in an advantage

00:09:52.380 neck position. We have a different problem though. And that is that people tend to, and I don't want

00:09:57.220 to mess up the sound and microphone, but they tend to hyper extent. They tend to bring their head

00:10:04.380 forward to come up to the oculars. And that creates a whole other set of problems. So there

00:10:10.660 are ergonomic challenges for sure. And I remember early on in my career, I was, I was coached very

00:10:18.380 carefully on how to sit, how to have your spine arranged. Don't crane your neck forward and make

00:10:25.940 sure that your shoulders are down. It's interesting because when you train surgeons and you look at

00:10:31.240 them, they're all sort of raising their shoulders up and they're terrified that they're going to do

00:10:37.500 something wrong. So they're in a very, very compromised and stressful position. And then

00:10:43.120 they tend to lift their hands up. So they're actually, and again, I mentioned earlier that

00:10:48.360 these are little tiny movements. So very small positional changes can have a huge impact on the

00:10:54.500 outcome of the surgery. Yeah. I have a number of friends, two in particular from residency who

00:10:59.540 have had multiple neck surgeries, including one that required such a significant extent of fusion

00:11:05.400 that he could no longer operate. So he trained as a cardiac surgeon and now does cardiac critical

00:11:10.240 care. So still a great career, but you know, after 10 years of training as a cardiac surgeon,

00:11:15.720 can't operate anymore. Yeah. I mean, surgery, it takes a toll on the, on the surgeon for sure.

00:11:20.540 So when you went to medical school, did you know you wanted to do ophthalmology?

00:11:23.180 Not really. I think I knew I wanted to do something surgical. I wanted to do something

00:11:29.020 with my hands. I'd kind of always been good with my hands and I could draw reasonably well. And,

00:11:34.580 and, and you get, as you kind of know, you get feedback early on in your medical career. If you

00:11:41.600 demonstrate that you're decent with your hands, people say, Hey, you're pretty good with your hands.

00:11:46.400 You should think about something surgical or maybe not. They say, have you thought about radiology

00:11:51.520 or something along those lines. And so I kind of knew that I wanted to be a surgeon,

00:11:56.500 but really didn't know what type. And I remember a eureka moment where the first time I looked

00:12:04.700 through what we refer to as a slit lamp, which is basically like a microscope to look into the eye.

00:12:12.740 The very first time I looked through that instrument at an eyeball, I was hooked. I knew this is what I

00:12:18.560 wanted to do. And that was something you did during an ophthalmology rotation? Or were

00:12:21.500 you doing an ER rotation and somebody came in with something stuck in their eye?

00:12:25.400 It was during an ophthalmology rotation. And I'd had some exposure to ophthalmology because a friend

00:12:31.900 of mine's father was an ophthalmologist, quite a famous one. And I'd had a background in photography

00:12:37.420 when I was a little kid. So I kind of understood optics well, but that was during one of those one

00:12:43.720 week, do a little ophthalmology, do a little ear, nose and throat, do a little bit of whatever it is.

00:12:49.720 And that was, that was the nice thing about medicine is that you kind of get to taste a

00:12:53.760 little bit of everything before you decide you're going down a particular pathway.

00:12:59.320 It's funny. I didn't really overlap with ophthalmologists. So you guys didn't do a

00:13:02.780 general surgery internship, I'm guessing, right?

00:13:05.400 Some of us do that. I did what is referred to as a transitional residence internship where you do a

00:13:11.340 little bit of everything. You do general surgery, internal medicine, you, you know,

00:13:16.020 you do a little bit of everything and that's, that's very helpful. And the general surgery part,

00:13:21.040 I will confess that was rough. I mean, as, as you well know, but it was nice to have exposure to a

00:13:28.520 little bit of everything.

00:13:29.880 That's probably a four-year residency, I'm guessing.

00:13:32.460 When you include the internship, that's right.

00:13:34.360 Yeah. Back in the day when you did it, how, what was the bread and butter? You, you always kind of

00:13:40.240 judge a discipline by what the bread and butter is of the era, right? So general surgery,

00:13:44.620 if you did it in the 1960s and 1970s, the bread and butter would have been Bill Roth procedures and

00:13:49.720 things like that, where the most common thing you were doing was cutting out half of the stomach

00:13:53.720 because of peptic ulcer disease and things like that. By the time I got to residency,

00:13:58.240 like I never did one of those, right? Because H2 blockers and PPIs basically eliminated the need

00:14:03.940 to surgically remove part of the stomach for gastric or peptic ulcers. So at the time you went

00:14:09.900 through your training, where did 80% of the volume come from? What type of cases?

00:14:13.900 Yeah. Still cataracts. Cataract surgery and then retinal disease. The scourge of essentially

00:14:20.100 diabetes where you had these very, very complex retinal problems. So those were really the two

00:14:27.220 main ones. So that's probably a good moment to sort of take a step back and get into some of the

00:14:32.220 anatomy and get me up to speed and everybody else by extension on what it is we are talking about

00:14:37.980 here. Because even the word retina, cornea, these are like, I kind of know the retinas at the back

00:14:43.780 of the eye. That like, it's just embarrassing, Stephen, how much of a Luddite I am when it comes

00:14:49.860 to this part of the body. So I can say this, literally talk to me like I'm a four-year-old.

00:14:55.680 Okay.

00:14:56.180 Explain the eye to me.

00:14:57.460 That's good. That'll work for both of us. So it's funny you mentioned that because I don't

00:15:01.520 typically see kids in my practice, but there is one disease state where I do see kids. And that's

00:15:07.780 because we did some research in that area that anyway, allows me to see kids. And when you explain

00:15:14.140 the eye to a kid and you say, well, the eye is like a camera and the film in the back, that's

00:15:21.640 the retina. And they look over at their parents like, what is this guy talking about?

00:15:26.900 Isn't a camera the thing on your phone?

00:15:28.820 What is he talking about? Film? What is that? A 50-year-old understands that,

00:15:36.180 but literally the eye is kind of built like a camera where in the very front, you have the

00:15:41.840 cornea, which is kind of like the covering on the front of a watch. That's the thing that a

00:15:46.120 contact lens would sit on. And then the next thing you encounter is the pupil, which is the hole in the

00:15:53.000 iris. Behind that is the lens. We refer to it as the lens, but it's really one of a couple of

00:16:00.600 different lenses inside the eye, but the lens behind the pupil, then you have the vitreous cavity.

00:16:07.620 And then in the very back, the retina, which attaches to the optic nerve. And that's what goes to the

00:16:13.280 brain. So images come in, they're bent by the cornea first, then bent again by the lens. And then

00:16:21.040 they focus hopefully on the retina. So in a perfectly sized eye and someone who doesn't need

00:16:27.600 spectacles to see images come from say optical infinity, which is for the purposes of our

00:16:34.640 discussion, about 20 feet or beyond where light rays come in parallel and they're bent so that they

00:16:40.940 fall perfectly on the retina. And what does that mean fall perfectly on the retina? Meaning

00:16:46.420 if you think about the back of the eye here, what fraction of the back of this sphere is considered

00:16:53.780 retina? All of it. Everything. Yeah. All of it. The whole back of the eye is coded essentially by 1.00

00:16:59.640 retina, but there is the fovea you mentioned earlier. That's the point where you cast your gaze.

00:17:06.120 So the image that of the thing you're looking at falls on the fovea, which is the very center,

00:17:12.680 the bullseye literally of the retina. So when I'm looking at you, images from you are falling on

00:17:21.000 the fovea of both of my retinas. Now, if someone is nearsighted, those images come into focus

00:17:30.520 in a point that is not exactly on the retina. And so that can become a problem.

00:17:38.520 And nearsighted, again, the way I used to remember this, because this is literally how

00:17:42.660 little I know. Nearsighted means you see things near well.

00:17:46.780 Yes, that's right.

00:17:47.480 And those are people like me who need either glasses or contact lenses to see things at a

00:17:51.980 distance.

00:17:52.480 Correct. So this is typical cocktail party banter. Someone will say, I think I'm nearsighted or

00:17:58.940 maybe I'm both nearsighted and farsighted. So nearsighted means you see better up close.

00:18:05.120 Farsighted is a little trickier because farsighted people see better at far, but their far might also

00:18:15.100 be kind of blurry. It's just that the near vision is even worse.

00:18:19.040 So that person who says, I'm near and farsighted, that's an accurate statement. That's a plausible

00:18:26.040 pathology?

00:18:26.820 Well, it's actually probably that they're what we refer to as presbyopic, which is that they see

00:18:32.060 well far away, but their focusing ability is compromised typically through age and they

00:18:39.920 can't see up close. And we'll get into that.

00:18:42.720 I want to get to that in detail because I experienced that a few years ago in a manner

00:18:47.660 that rocked my world because it didn't happen gradually.

00:18:51.160 Yeah, that seemed to happen overnight.

00:18:54.080 And so, yeah, it's funny you say that. Some people wake up on their 40th birthday and they

00:18:58.360 say, I just can't see up close anymore. And for others, it's a little more gradual process.

00:19:05.080 But the reason that comes into play is that when we are young, when we're born, the lens of our eye

00:19:13.720 eye is extremely elastic. It's like a gummy bear and it can change shape to bring near objects into

00:19:23.500 focus. But as we age, and this is universal, the elasticity of the lens goes down and we're no

00:19:32.480 longer able to sort of zoom focus in and you have to start pushing things farther and farther away

00:19:41.260 or get some sort of optical aid like a pair of spectacles to see up close. That process continues

00:19:49.300 as the lens becomes less elastic and harder, eventually resulting in a cataract where it begins to

00:19:56.620 lose its optical clarity. So now you have a lens that's stiff, hard, and starts to become opaque.

00:20:07.060 So a cataract is a disease of the lens.

00:20:09.500 Correct.

00:20:09.840 And it's a natural, I guess this is kind of a gray area. Do we consider this to be a natural

00:20:16.720 product of aging the way our skin wrinkles and the elasticity changes? Or is it considered

00:20:22.960 a pathology in the way that type 2 diabetes is a pathology, not necessarily a normal consequence

00:20:29.680 of aging that can be avoided?

00:20:31.340 Yeah, that's a really good and interesting way to look at it. So I think that cataract formation is

00:20:37.460 a universal component of DOE days on earth. I don't recall seeing many people in their 70s without some

00:20:48.500 degree of cataract formation. It starts to become universal. However, there are things that can

00:20:55.620 pathologically prematurely cause cataract formation. Some of them are sort of surprising, like being

00:21:02.740 electrocuted can actually cause premature cataract formation. But that's one sort of exotic weird

00:21:09.620 one. But trauma, head trauma can certainly do it.

00:21:13.300 Just head trauma, not necessarily eye trauma.

00:21:15.220 Well, you know, the head-

00:21:16.500 I mean, obviously they go hand in hand, yeah.

00:21:18.500 Typically, the eye is in the head. And if the head receives trauma, there's going to be a certain

00:21:24.340 amount of trauma in the eye itself.

00:21:26.100 Right. But point is, it doesn't have to be direct trauma to the eye.

00:21:28.500 Correct.

00:21:28.740 Simply, the coo-counter-coo forces of the brain are presumably also being reverberated through the

00:21:36.820 vitreous fluid.

00:21:37.620 That's exactly right. So if you think about, you know, the eye is a fluid-containing organ. And when

00:21:43.540 it receives trauma, and just as you mentioned with coo and contra-coo injuries of the brain inside the

00:21:51.300 skull, I think those same forces come to bear on the eye itself. So I think it's more common when you

00:21:58.180 do have direct eye trauma, but I think even head trauma alone can predispose someone to cataract

00:22:04.340 formation. Certainly diabetes is a cause of premature cataract formation. Steroid use,

00:22:11.860 corticosteroid use can lead to cataract formation. So is the lens of vascular structure?

00:22:18.260 It is not. And the protein, if you think about the lens, it's kind of the shape and about the size

00:22:26.260 of an M&M candy. Just like a plain-

00:22:29.540 The chocolate ones.

00:22:30.420 Yeah, the chocolate ones, right? Just the ones without the nuts or pretzels or whatever they're

00:22:34.740 putting inside M&Ms now. But the, you know, a plain M&M candy. And it's got a coating kind of like

00:22:42.580 the candy shell. And the protein inside the chocolate is optically clear when you are a kid.

00:22:51.140 And that protein does not turn over or exchange, but the membrane, the candy coating, the so-called

00:22:59.460 lens capsule can allow molecules to diffuse in and out. So a classic example of this is someone will

00:23:09.700 point out, hey, my vision, my glasses prescription suddenly changed. I became much more nearsighted,

00:23:17.780 or I became much more farsighted in the space of a month. And I went to the eye doctor and they

00:23:22.980 said, wow, your glasses are totally wrong. And the first thing I think of is go get your blood sugar

00:23:28.180 checked because glucose can diffuse into the lens, cause it to swell. And that will change the shape

00:23:36.900 of the lens. The lens becomes physically bigger. So it's like a thicker, more powerful lens.

00:23:42.260 So it's an osmotic change. Correct. And the timeframe for that to happen is over a period

00:23:48.660 of several weeks. So if the blood sugar goes up, it may, there may be a lag of a month or two before

00:23:55.300 the vision changes. And when the blood sugar goes down, same thing. It takes weeks for that to kind

00:24:00.500 of go back to normal. So again, I'm just so, I'm almost struggling to organize my thinking around

00:24:07.860 this, but the other thing that comes to my mind when you think about an avascular structure

00:24:12.820 is what is the immune system's behavior around the eye? Are these immune privilege sites? Are they

00:24:20.980 more or less susceptible to certain types of infections? Systemic infections, that is. Obviously,

00:24:25.300 I know we'll probably talk a little bit about sort of local infections, but.

00:24:28.580 Yeah. I mean, the eye itself is certainly prone to damage from systemic infection.

00:24:34.340 There is a blood retinal barrier in the same way that there's a blood brain barrier that protects

00:24:39.380 that highly metabolically active retina from systemic disease. But the lens itself is relatively

00:24:47.700 privileged from an immune standpoint. It's within that capsule and it's hard for large molecules to

00:24:54.020 get across that. Small molecules can. That's going to be important from a pharmacotherapy standpoint.

00:24:59.220 It is. And for example, there is a technology, there's a medication that is a lipoic acid choline

00:25:07.220 ester that is being examined as a way of softening the lens to maybe break some of the disulfide bonds

00:25:15.940 that become a problem and become one of the reasons why the elasticity of the lens is lost.

00:25:23.540 So you're saying there might be a day when there's either a topical or injectable

00:25:28.020 substrate that could go into the lens that could delay the onset of farsightedness.

00:25:32.500 And the onset of cataract. That's the hope. This is sort of at the moment,

00:25:36.660 it's a little bit of a pipe dream because it's in the early experimental phase, but human trials have

00:25:42.660 begun to look at the lens softening properties of this particular compound. The trick is you've got to

00:25:50.500 use it in a topical fashion. So putting in an eyedrop and that drop has to run the gauntlet of

00:25:57.140 going through the cornea, which has lipid layers and water soluble layers. It's got to get through all

00:26:04.740 that into the aqueous humor in the front and then through the lens capsule into the lens to actually do

00:26:10.660 its work. And that's why it's that particular drug or compound is a choline ester because that allows it

00:26:17.380 to get through the lipid layer in the front, through the aqueous, through the water soluble

00:26:22.420 portion of the cornea, and then hopefully into the lens itself. And that's not easy to do. So the lens

00:26:28.900 is a relatively privileged area, both from an immunological, but also a pharmacological standpoint.

00:26:34.820 So that helps it also stay clear. Yeah. It's got to, you want the lens to be optically clear.

00:26:42.020 Let's go back to a little bit of the front of the eye. So the pupil we all recognize is the dark

00:26:46.660 part. And we talk about the dilation and constriction of the pupil. Is the pupil itself

00:26:51.780 actually changing in size or is it just that the iris is moving the colored part of the eye?

00:26:57.300 Dilation means it's actually moving back and constriction means it's actually closing.

00:27:02.180 That is correct. It's the physical aperture changes in size. It gets bigger, it gets smaller. So when

00:27:07.860 they, when you go to the eye doctor and they dilate your pupils, they are physically opening up

00:27:13.060 the pupil pharmacologically. And that's mostly so we can see into the back of the eye.

00:27:19.220 And you do that by forcing the iris to move out of the way?

00:27:22.340 Correct. The iris has a, it almost looks like the aperture of a camera. You can either constrict it or

00:27:29.140 you can make it bigger. And interestingly, one of the big pharmacological, I think, frontiers that

00:27:36.740 we're on the cusp of seeing are drugs that intentionally shrink the aperture in the pursuit

00:27:44.420 of increased depth of focus. So students of photography will know that the smaller the

00:27:51.060 aperture, the smaller the hole, the more stuff is in focus at the same time. So if you can make the

00:27:57.700 pupil small pharmacologically and get it into the sweet spot, which is probably about 1.6 millimeters,

00:28:04.100 you can suddenly see up close again because you've expanded the depth of focus.

00:28:09.780 Wait, this is, let me make sure I understand this. You're saying that putting the lens aside

00:28:15.700 for a moment, which is a great source of the pathology, the inability of the lens to move in

00:28:21.940 and out on the, call it the Z axis. If we want to think of it that way, you now have another way to

00:28:27.860 manipulate your ability to see things close up. If you could force the aperture to be in a

00:28:33.940 position that isn't necessarily dictated by the availability of light?

00:28:36.980 That's exactly right. So imagine, it's kind of like squinting. If you squint, you're reducing

00:28:43.620 the aperture through which you're looking. And you're filtering out, optically what's happening

00:28:49.060 is you're filtering out all of the light rays that are not perfectly parallel. And if you can get rid of

00:28:55.300 those scattering rays that make the image blurry and only use those parallel rays that happen to be

00:29:02.740 coming parallel off of an object, you can actually resolve it. You can actually see it. And that's

00:29:09.140 why pharmacologically, if you shrink the pupil, you could once again, see up close.

00:29:15.860 Now, this is, again, is a little counterintuitive to me because anybody who's in my shoes, who's

00:29:21.780 experiencing farsightedness, or I shouldn't say that, Presby. Presbyopia. Presbyopia knows that

00:29:29.700 nothing makes it worse than darkness. There's two scenarios where it wreaks havoc. The first is

00:29:35.860 one of my children has a train book that why these guys wrote a book in like six point font that they know

00:29:44.580 parents are going to read their kids in bed when it's kind of dark. It's beyond me. Like there

00:29:49.380 should be a mandatory 24 point font for nighttime books for little kids. But anyway, he's got this

00:29:54.740 one book and he even tells me before he wants that book, right? He's like, daddy, go get your glasses.

00:30:00.740 And then the other place is the restaurant where it's usually poorly lit. But in both of those

00:30:05.140 situations, isn't my aperture narrowed because, oh no, no, of course not. It's the opposite.

00:30:09.380 It's the opposite. So if you put the sun on something, you're going to be able to read it

00:30:13.780 because you're a pupil. So is that why light makes it different?

00:30:17.940 Some of it is just the, absolutely. It's pupil effect alone.

00:30:21.540 I never thought of that. And some of it is just the light,

00:30:23.220 there's much more light energy available for you to resolve something. So yes, there are competing

00:30:29.220 forces when you reduce the size of the aperture, you're letting less light in. But the only light

00:30:35.780 you're letting in are those rays that happen to be parallel in perfect focus and you can actually see.

00:30:41.460 So in the clinical trial that we performed to look at this, those competing forces were examined very

00:30:50.820 closely. And we found that the aperture effect, the depth of focus outweighed any loss of vision

00:30:58.180 from loss of light. And how long would these eye drops stay in effect? How long would they be able

00:31:02.980 to maintain after you put them in? I think about, it depends a little bit upon eye color, believe it

00:31:07.700 or not, because... Something I want to ask about in a moment, so I'm glad you brought that up.

00:31:11.860 Yeah. Certain eye color, like light eyes tend to react more to any given strength of dilating drop or

00:31:19.860 constricting. But about six to eight hours, maybe up to 10 hours. So this would be a once a day,

00:31:26.420 maybe a twice a day eye drop. And would this have any impact, would it compromise your far vision?

00:31:34.180 Quite the contrary. What was really interesting is that when we looked at patients who had their

00:31:41.300 pupil size reduced pharmacologically, their distance vision also gets better by the same principle,

00:31:48.660 because their depth of focus is so good. So in the same way that you can squint and make out

00:31:54.820 a highway sign, if you're a little bit nearsighted or a little bit farsighted or have a stigmatism,

00:32:00.820 which we haven't even talked about yet. Yeah. Which I don't even know what that is,

00:32:03.060 even though I have one. That's right. And squinting makes that better. By the same token,

00:32:08.420 the pharmacological manipulation of your pupil will do that as well. And by the way,

00:32:13.220 I think you will see in early 2022 commercial availability of these, of the first of these drugs.

00:32:21.300 So going back to the more complicated drug you were talking about that has, it's complicated because

00:32:28.980 it has to make its way into the lens. I can now see why that would be more about the cataract issue

00:32:34.980 and not about the presbyopia issue, because this would be a much easier way to solve presbyopia,

00:32:40.340 because you only have to basically get onto the iris. Yeah. Well, you're looking at a drug that

00:32:46.740 shrinks the pupil and works in 15 minutes versus something that softens the lens that might work

00:32:53.220 in 15 months. So I think they're very different markets. And while that lipoic acid choline ester

00:33:01.860 is being pursued as a presbyopia near vision aid or something to reduce the effects of, I think their

00:33:11.780 real goal is to reduce the incidence or delay the onset of cataract formation, which would be really

00:33:19.300 cool. Yeah. Is there any clear evolutionary explanation for why different eye colors have

00:33:25.620 emerged? What's the advantage of brown iris versus blue? Yeah. It's a protection from UV light and from

00:33:31.780 visible light. And in the same way, the different skin tones have emerged. So typically you see dark eyed

00:33:38.100 people clustered closer to the equator because, you know, the visible light and UV light and infrared

00:33:45.300 light or infrared radiation are really destructive. And as you might remember, this is one of the few

00:33:54.900 things that people remember from medical school about the retina, but it's one of the most metabolically

00:33:59.780 active tissues in the body, if not the most metabolically active tissue. And because it's constantly being

00:34:06.340 bombarded with radiation effectively, it's prone to free radical formation. So what's called the

00:34:14.580 retinal pigment epithelium, which is the pigmented layer behind the retina, underneath the retina,

00:34:22.820 that is responsible for shielding the vascular supply behind the retina from all of this radiation.

00:34:32.340 Because that vascular network behind the retina has a very high oxygen tension and it would be

00:34:39.780 prone to free radical formation if it were constantly being bombarded by UV light, infrared

00:34:44.740 radiation, visible light. And that's why you see in people near the equator, more pigment. And that's

00:34:51.700 also true of the iris as well. So the other thing I do remember vaguely from medical school is rods and

00:34:58.340 cones. And of course, I also remember a few other things now that we're talking about it about which

00:35:04.660 part of the brain actually does the signal processing and stuff. So let's go back to the light hitting

00:35:11.540 and what are the rods and cones and how are they processing that signal?

00:35:16.180 You might remember cones are primarily for your daytime vision and they're clustered in the center of your

00:35:23.620 visual sphere. So near the center of the, what we refer to as the macula, which is a central portion

00:35:29.620 of the retina. And the very center of the macula is the fovea, right? So that's primarily where the

00:35:35.700 cones are. The rods are in the periphery and they typically are responsible more for dim illumination

00:35:43.620 vision, like night vision. And they're very good at picking up motion. So as predators, we

00:35:49.540 want to make sure that we can hone in on where prey is, but as prey ourselves, we want to be able to

00:35:56.820 detect, oh, that's a, some kind of a tiger over there. Something's moving in my periphery. I need

00:36:02.660 to be aware of that. So that's primarily the difference in responsibility.

00:36:07.300 And is each rod and each cone, is each one a single cell?

00:36:11.220 Yes, that's right. They're each highly specialized cells.

00:36:14.180 Obviously they have mitochondria. What distinguishes them? Do they have

00:36:19.140 photoreceptors? Like what makes them unique?

00:36:21.300 They are photo, they refer to as photoreceptors and they have stacks of structures within them that

00:36:28.020 are photosensitive and that causes a depolarization.

00:36:31.860 So they work like channel opsins do? They use a photon to create an action potential?

00:36:36.740 Correct. Once the photon hits that particular cell photoreceptor,

00:36:41.220 then there's a change in the membrane and ions flow and that's how a signal is generated.

00:36:46.900 Wow. Okay. So all of that ion flow ultimately makes its way to the optic nerve?

00:36:55.620 Correct. That's right. And to the brain. And most of the visual processing is in the very back of your

00:37:01.220 brain and about half of the overall brain structure deals with vision in some capacity. And that's why,

00:37:08.660 for example, when people have a stroke, there's almost always some component of visual involvement

00:37:16.420 in a stroke. So you may have a droopy face on one side and then a limb is droopy as well. But if you

00:37:23.940 map out the visual sphere, you will detect some deficit in the visual sphere from most strokes.

00:37:31.620 Now, people who listen to this podcast on various episodes, we've got into the brain and people

00:37:37.780 understand that I think there's sort of the brain stem, the most primitive piece of our brain that

00:37:42.660 is basically responsible for autonomic function. You then have sort of this mid brain that sits on

00:37:47.620 top of it that we call the sort of reptilian brain, a lot of emotion there. But of course,

00:37:53.380 what in theory distinguishes us from all the other animals is this remarkable cortical piece that sits on

00:37:58.900 top of it? And how much of the visual processing is in that neocortex? Is it virtually all done there?

00:38:05.620 Yeah.

00:38:05.940 Is any part of it done in the midbrain?

00:38:07.460 Yeah. Stuff like pupil responses.

00:38:09.460 The autonomic stuff.

00:38:10.580 The autonomic stuff. Those are in the midbrain. But the visual processing and the actual mapping of

00:38:17.300 the visual sphere and even as hierarchical as parts of the brain that are specific to edge detection

00:38:28.180 or moving edge detection or edges that move this way or that way, that's all been mapped quite elegantly

00:38:35.700 and it's in the cortex.

00:38:36.980 Is there a cross? Is the left doing the right and vice versa?

00:38:40.500 That's right. But remember, you send information from your left visual sphere to the right side of

00:38:47.140 the brain, but you're getting information from both eyes.

00:38:51.700 Yeah.

00:38:52.580 So both eyes, yeah.

00:38:54.820 Explain how that works because I remember in med school needing to draw this a few times to get it.

00:38:59.380 How long do you have?

00:39:01.380 The simplest way to think about something is that at the pituitary, there is something called

00:39:07.380 the optic chiasm. You probably remember where the optic nerves kind of cross.

00:39:12.180 Right. Some of the fiber, about half the fibers cross.

00:39:15.380 So if a visual deficit is in one eye only, we know that it is in front of the chiasm. 0.91

00:39:21.940 Correct. That's right.

00:39:22.820 And if it's behind that, it should affect both eyes. Maybe asymmetrically, but it should affect

00:39:27.460 both eyes. And that could be very helpful in localizing where a particular problem is.

00:39:33.620 Now, a lot of that's done through imaging, but it used to be there was quite an art to

00:39:38.420 this clinical to this clinical exam, which, you know, sadly, we've lost a lot of.

00:39:43.300 Yeah, this is and I do remember both in neurology and probably neuroanatomy kind of going into these

00:39:52.420 really crazy tests that you'd see the patient performing the test and missing a certain thing.

00:39:58.740 And you'd think they must be faking it like there is no way you could produce such a bizarre

00:40:04.020 deficit in this one part of this one visual field. But then, of course, you see and look,

00:40:08.260 there's a tumor and it totally explains this once you understand how the nerves cross.

00:40:12.420 It kind of goes back to one of your earliest questions, which is, do you think that eye

00:40:15.940 surgeons need to go to medical school? Yes, because we diagnose brain tumors. We find things that are

00:40:23.380 systemic diseases that have ocular manifestations. So you're obviously well aware that your brother

00:40:30.340 and I are close friends and he's become pretty obsessed with hunting now. And I'll take full

00:40:35.620 responsibility, at least for the part of it. I did not see this one coming.

00:40:38.740 Yeah. Well, you'll see where this is going, right? So he's become super obsessed with hunting. And

00:40:44.660 one of the things that hunting teaches you is how we stack up to wild animals. So if you're out hunting

00:40:53.140 an elk or an axis deer or one of these remarkable creatures, especially with a bow and arrow.

00:40:59.220 Yeah. I was going to say, how much technology do we have access to in this hypothetical scenario?

00:41:03.300 So no, let's talk about bow and arrow hunting where you really, I mean, if you really want to reduce

00:41:08.580 the margin of error, you want to be inside of 50 yards to be able to take that shot.

00:41:13.220 So the way I always talk about this is animals have superpowers and we just have to decide,

00:41:19.140 as do we, we have superpowers, our greatest one being our intelligence, which allowed us to make

00:41:24.660 the bow. But I generally think of the three big senses, right? Which is the sense of vision,

00:41:31.300 the sense of smell, the sense of hearing. And there's simply no comparison in sense of smell.

00:41:39.460 We basically can't smell. We're effectively useless creatures in nature.

00:41:44.100 Agreed. Yeah. 0.56

00:41:44.820 If they're downwind of us, they can smell us a mile away. Literally one mile away. If the wind

00:41:51.220 moves from you to them, they're gone. You'll never get close to them.

00:41:56.020 It turns out that the closest sense we have to our prey is vision. It's the only thing where we're

00:42:05.140 almost on par with them. Now, there are some animals that can see better than us. There are

00:42:09.620 certain types of rams that if you break skyline within two miles of them, they'll see it.

00:42:17.220 And birds.

00:42:18.020 Yeah. But for the most part, this is the one sense that we have that rivals the best.

00:42:25.780 Is that because we both had to, as you said, be hunters and be hunted for such a large part of

00:42:31.940 our revolution? Is that, I mean, this is sort of teleologic explanation I'm looking for, but.

00:42:36.420 Well, I think so. But just think about this for a moment. Imagine you are in the desert

00:42:42.500 and there is a single candle a mile away from you and it's pitch black. There's no moon.

00:42:49.060 You can see that. But at high noon in that same desert where there may be 200,000 lux illumination,

00:42:59.380 you can still function and see well. So many, many, many, many, many orders of magnitude of change

00:43:06.340 of illumination. It's astonishing that you can function in both of those environments.

00:43:12.100 Well, that's actually interesting that you make that point because as it gets darker,

00:43:18.260 we do tend to have an advantage over some of the animals. Now it turns out to be very short-lived.

00:43:23.700 There's a very narrow window at dusk and dawn where I think we can outsee them. And maybe that's the

00:43:29.780 benefit we have in that we evolve slightly better to have this greater range, if you will. But I've

00:43:37.060 always been amazed at why did we not develop a sense of smell? Because we effectively can't

00:43:43.140 smell compared to animals. I mean, it's really absurd how different it is. And I don't know why

00:43:48.660 evolution didn't push that harder. And even our hearing, I think, we're not even close.

00:43:54.340 Nothing compared to them.

00:43:55.300 Yeah. But vision, and if you ask, it's very common for patients to grab my arm as we're going into

00:44:03.060 surgery and they'll say, Dr. Dell, you don't understand. My vision is really important to me.

00:44:09.140 I've got to see. I've got to see. And I get that. It's the one sense that if you asked people which

00:44:16.660 sense they'd be most willing to give up or least, it's the very last.

00:44:20.340 This is the last one. And in COVID, we saw many people at least transiently lose a sense of smell

00:44:25.380 and a sense of taste. And of course, it's inconvenient, but it's totally survivable.

00:44:29.940 Yeah. It's hard to function in the world as a blind person. And it's a fear that many of us have.

00:44:37.540 So it's a sense that we value very highly. And also, evolutionarily, it's valued highly,

00:44:43.220 just owing to the fact that so much of our brain is devoted to vision.

00:44:46.220 Yeah. This is a little bit off track, but maybe good for a PSA. When I was a kid,

00:44:51.900 we did so many dumb things without ever any concern for our eyes. I just don't think our

00:44:57.900 parents knew enough and we didn't think about it. So I'd be out in the backyard, chucking things

00:45:04.620 around, cutting wood, smashing rocks, never a thought to put on safety goggles. And now my kids,

00:45:12.300 kids who are both completely obsessed with cutting down trees and they're very active outdoors.

00:45:19.820 I mean, they just know you're wearing your safety goggles if you do that stuff because I'm totally

00:45:24.860 paranoid they're going to have one of these tragic accidents. Do you see much of that stuff?

00:45:30.220 For sure. And you see a lot of eye injuries. I think injuries are one of the main causes of

00:45:38.620 devastating visual loss in young people. If we take visual loss in general, almost all of the big

00:45:46.700 causes and movers of visual loss are senescence-related or age-related. But in terms of vision

00:45:53.340 loss in young people, it's a lot of trauma.

00:45:55.420 And what are the most common traumas that you see? Is it object flying into eye or is it more-

00:46:02.620 I think it's more blunt trauma, frankly.

00:46:04.060 Okay, wow.

00:46:04.860 Yeah, more blunt trauma. The eye is pretty well protected with the brow and the cheek,

00:46:09.420 but there are certain things that can get in there and can directly impact the eye. And so I think in

00:46:17.900 a young person, trauma is something you have to certainly watch out for.

00:46:21.740 What is the velocity at which we can't out-blink it? Because the other day my son was smashing

00:46:27.820 beads and he didn't want to put his safety goggles on. And I was like, look, buddy,

00:46:34.220 you got to get these things on. And he goes, no, dad. And he's like, why? And I said, because

00:46:38.060 you're hitting sharp objects with a sharp object. If one of them flies up and hits your eye, he goes,

00:46:42.620 I would see it and I would close my eyes.

00:46:44.860 No, you wouldn't, buddy.

00:46:46.300 Yeah. Let's just put it this way. Those objects are flying at supersonic speed

00:46:50.700 and you can't blink that fast.

00:46:53.260 So do we have a sense of what our reaction time is to blink?

00:46:57.020 That is known, but I've long since forgotten what that is.

00:47:00.220 Because you get the sense, if somebody's throwing you a ball and you misjudge it,

00:47:05.260 you're going to blink. That's slow enough that you can catch it. But then there's other objects where

00:47:11.100 you can't. Interestingly, I've operated on a number of major league baseball players.

00:47:17.420 And for them, seeing the laces on the ball as hitters is enormous.

00:47:20.940 It's their career.

00:47:21.900 It is their career. And it's the difference between them hitting well or average. And some of these

00:47:27.580 players that we've operated on have been 20-20 before they had surgery, but they wanted to be

00:47:34.460 20-15 or 20-10. And what that means is, again, here's another nomenclature issue. What is 20-20?

00:47:40.940 20-20 vision? 20-20 simply means that you can see at 20 feet what a quote-unquote normal person

00:47:49.500 can see at 20 feet. If you're 20-10, you can see at 20 feet what a normal person has to get 10 feet

00:47:57.980 up to in order to see. So 20-10 is better than 20-20. So some of these guys want to be 20-10 or 20,

00:48:06.300 whatever it is, 2015. We've been able to achieve that with modern forms of laser vision correction

00:48:12.860 because- Wait a minute. Isn't this now getting into the performance enhancing side of things?

00:48:17.740 Isn't this kind of amazing? I never even thought of this.

00:48:20.460 Yeah, for sure. And I had a discussion yesterday with a guy who owns a soccer team. And I said,

00:48:28.700 have you ever had your players tested for their vision? And he sort of froze and turned white for

00:48:35.260 a second. He just said, it's so crazy you say that because we put them through this barrage of tests

00:48:41.660 physically to see what their heart, their lungs, their kidneys, all that stuff. We didn't check their

00:48:46.780 vision. And there are ways to boost human performance beyond 20-20. The theoretical limit

00:48:55.020 of how well you could see is defined by essentially the pixelation of your retina,

00:49:00.940 the spacing of the cells of those photoreceptors that we talked about earlier.

00:49:04.540 Does that vary from person to person?

00:49:06.380 It has to, but it's somewhere in the vicinity of about 20-08 or so. So if you can have a sharp enough

00:49:15.180 image, you could theoretically see better than 20-10. And the only way you can really achieve that

00:49:21.980 is to remove some of the optical irregularities that we are all born with and somehow neutralize

00:49:29.660 them along with the glasses prescription. And we can actually do that with laser vision correction

00:49:36.300 currently. So why would it be beneficial? I guess we'll talk about laser surgery and maybe

00:49:43.020 you'll want to park this question until then. Why would it be beneficial to an athlete who,

00:49:47.900 for understandable reasons, needs the best vision possible to undergo laser corrective surgery versus

00:49:54.940 just using contact lenses to accomplish the same thing? Is that possible?

00:50:00.860 Yeah. So if you think about contact lenses, anyone who's ever worn contact lenses knows that when you

00:50:07.100 put in a brand new pair of contact lenses, you can see pretty well with them. And then you begin to

00:50:14.140 regard that contact lens as a foreign object. So your body just begins to attack it, coat it with

00:50:20.620 all sorts of immunological debris. You are susceptible to pollen, dust, whatever it is that coats this

00:50:29.820 formally pristine object. And let's say there is correction for astigmatism in that contact lens,

00:50:37.340 where its orientation is important. Every time you blink, that contact lens moves a little bit.

00:50:43.900 All of those factors contribute to optical performance that is less than what you can achieve with

00:50:50.940 spectacles or laser vision correction. Particularly soft contact lenses do a very,

00:50:57.180 very good job, but they don't give you super human vision performance typically.

00:51:01.740 You know, it's funny. I experimented two years ago with a stronger prescription than normal

00:51:09.420 to get me to 2015 in my dominant eye for archery.

00:51:14.380 Sure. Goofed up your near though.

00:51:16.060 That's the problem. I just abandoned it immediately after like six months of

00:51:19.980 suffering because it made my presbyopia worse.

00:51:24.620 Yes. So I was just like, oh, this just isn't worth it.

00:51:26.940 Yeah, that's right. That's the challenge. When you

00:51:30.940 pull the image farther and farther away, you're doing the same thing with the near image as well.

00:51:37.260 Let's now talk about how to correct these. I guess let's define an astigmatism since I don't

00:51:41.980 know what that is yet. Yeah. I mean, it's when the eye is shaped like a football instead of

00:51:46.700 a basketball. And when you say the eye, which part of the eye specifically?

00:51:50.300 The cornea, the very front part of the eye typically.

00:51:53.020 And how thick is the cornea, by the way?

00:51:54.700 It's about as thick as a credit card, like 500 microns.

00:51:57.500 Oh, that's thick.

00:51:58.060 Yeah. Yeah. Like 550 microns, something like that.

00:52:01.340 So half a millimeter.

00:52:02.060 Yeah, exactly right. So half a millimeter. And typically that is the location of astigmatism.

00:52:09.020 There can be astigmatism in the lens itself, the lens behind the pupil.

00:52:13.580 You probably don't remember which one I have, do you?

00:52:15.820 I do.

00:52:16.780 Which one do I have?

00:52:17.980 You have corneal astigmatism.

00:52:19.420 That's the normal one.

00:52:20.700 That's the normal one.

00:52:21.260 Yeah, it's very pedestrian. You're a very boring patient. 0.95

00:52:25.420 So meaning, just to be clear, I'm not perfectly shaped around here. I'm a bit oblong.

00:52:30.540 That's right. Shaped like an egg or a football, an American football. So if you're walking along

00:52:36.540 the laces of the football, you would encounter a fairly gradual curve. But if you took a right

00:52:41.980 turn and walked perpendicular, it would be very steep.

00:52:44.940 Okay. And so that means that the power differs by meridian. So you need a different glasses

00:52:53.500 prescription in this meridian versus this meridian. What's the prevalence of this?

00:52:58.060 It's very high. I think 60 some odd percent of patients with glasses prescription have some

00:53:05.500 significant degree of astigmatism.

00:53:07.340 Why has poor vision, or I was going to say, why has poor vision been allowed to evolve?

00:53:14.780 I was going to offer that maybe really poor vision hasn't, right? Vision that would impair your

00:53:20.780 ability to survive through reproductive age probably didn't evolve. Maybe there was a day when the genetic

00:53:28.780 variability of eyes was broad enough that a subset of people had really poor vision.

00:53:34.380 The type of people today who maybe we don't encounter.

00:53:37.420 Right. This is a super interesting topic and it shows you how plastic

00:53:43.500 the evolutionary or actually the adaptive component of the eyeball is itself. So the length of the eye

00:53:52.460 is really what determines whether you are nearsighted or farsighted.

00:53:56.060 When you say length, you mean distance from?

00:53:58.140 Front to back. So anterior, posterior, length of the eyeball. Primarily that is the main driver

00:54:05.180 as to whether you are nearsighted or farsighted. Those who are in the know and are watching this

00:54:11.420 or listening to it also realize that sometimes it's the curvature of the cornea that contributes

00:54:18.060 to whether someone is nearsighted or farsighted. But let's say for the purposes of this discussion,

00:54:23.020 that it's the length of the eyeball that is the main reason why someone is nearsighted or not or

00:54:29.980 farsighted. So a very nearsighted person has a very long eyeball. Let me make sure I understand that.

00:54:37.340 Very long AP axis. You're going to have a real hard time seeing things far away. And is that because

00:54:44.860 the further something is, the harder you have a time focusing all that light?

00:54:50.380 Well, let's talk about the genesis of this. So if most of your work, most of your visual

00:55:01.180 environment is close, then the light rays from that close object are diverging.

00:55:07.340 So they are falling behind the retina of someone who's perfectly targeted for distance. So your

00:55:16.780 eyeball is really smart and it says, okay, so you're telling me everything is here close up.

00:55:23.580 I know I'll just grow longer so that these near objects are in perfect focus. And that is exactly

00:55:31.500 what happens.

00:55:32.700 Over what time scale?

00:55:33.900 Over a period of months. So if you take a young person and you exclusively have them perform near

00:55:42.940 tasks, their eye will grow longer so that those near objects are in perfect focus.

00:55:51.820 So if you could do an awful experiment, you would take a child and not put them in a white room where

00:55:59.180 there's nothing that they can see that's far away and just have them play with close objects that they

00:56:04.140 can reach. And you would put that kid into glasses as a child.

00:56:08.620 That's called society in 2021 is children looking at screens near objects for hours on end and not going

00:56:19.260 outside. There are two drivers of nearsightedness in the plastic developing human. Number one,

00:56:27.980 deprivation from outdoor light and number two, near work. So for example, there have been cohorts of

00:56:38.780 children. These, most of these studies have been done in Asia where there is an epidemic right now

00:56:43.820 of myopia of astonishing proportions. I'm talking about 90% of the population is now nearsighted in

00:56:53.180 certain Southeastern Asian cities. When that becomes such a dominant phenotype, something is 1.00

00:57:00.300 really oddly off. Wow. So this really transcends evolution because you can change, if you can change

00:57:06.780 something in years or months. Within the, it's not evolutionary. It's, it's within the eye. It's, it's

00:57:11.500 adaptive within the eyeball itself. So if you take a group of children and this has been done,

00:57:19.020 seven to 11 year old children, and you send half of them outside for 80 minutes during the school day

00:57:25.740 for recess and half of them stay inside in an indoor environment for their recess, the risk of,

00:57:35.580 or the incidence of nearsightedness is half in the group that went outside. So you cut your risk in half

00:57:41.820 by going outside. Without any instruction to go and look at things far away, but just by the very

00:57:47.260 fact that if you're outside, there's so much more to see and you're going to be looking further out.

00:57:52.220 Right. And this has been further studied in terms of, is it just being outside or is it the light?

00:57:59.900 It's actually both, but the light is really the most important driver of protection from nearsightedness.

00:58:08.460 So if you are outside on a bright, sunny day, you're releasing a fair bit of dopamine from your

00:58:14.780 retina and dopamine inhibits the growth of the eye. So the worst thing you could do is stay inside in a

00:58:23.740 dimly lit room and perform near tasks that raises your risk of nearsightedness 16 fold compared to kids

00:58:34.300 who go outside. I'm sure there's epidemiology that would suggest that the further you are from the

00:58:39.420 equator, does that imply that you have a greater risk of nearsightedness just based on the light

00:58:44.060 part of this argument? Yes. There is some data to look at that, that shows that. And not only that,

00:58:50.620 they've taken children and given them equal intervals of outdoor activity, but the ones who had

00:58:58.780 noontime outdoor activity did better than the ones who were outdoors at 8 AM where there was less

00:59:04.780 illumination. And we know from animal models that it is illumination that is critical in this dopamine

00:59:12.460 release. So does that mean we need more skylights in classrooms or more windows? We need more natural

00:59:20.700 light. Could we artificially mimic some of the sunlight by making these rooms brighter and prevent some of

00:59:27.180 this myopia epidemic? Is a photon, a photon, a photon? I mean, does it, I mean, I don't think that it's

00:59:32.780 known, frankly, Peter, whether that's the case because there's a whole spectrum of light. So is the blue

00:59:38.140 light more important? This is tangential and we'll talk about this, I know, but blue light, you hear all

00:59:44.940 this negativity about blue light. Blue light is critical for wakefulness, for attention, for, I think,

00:59:53.260 for preventing myopia. And by the way, when we say myopia, nearsightedness, it's not just the

01:00:01.900 inconvenience of wearing glasses or contact lenses or having laser vision correction when you're 23 years

01:00:07.740 old. There are pathologies that are much more common in very nearsighted patients compared to the general

01:00:15.100 population. It's much more common to see cataract formation in myopic patients. They get something

01:00:21.340 called myopic macular degeneration. They're at risk for glaucoma. They're at risk for tears and

01:00:30.140 detachments of the retina. So it's not just the inconvenience of spectacles. These are disease

01:00:34.860 associated conditions. So going back to my evolutionary question, it's quite possible that over hundreds of

01:00:42.380 millions of years, any deficit in vision that would have prevented you from reproducing or impaired your

01:00:49.180 ability to escape a prey would have taken that out. So from a genetic standpoint, our vision should be

01:00:53.980 very good. And in non-literate societies, it typically was. So if you look at hunter-gatherer

01:01:00.220 tribes, there is no nearsightedness. There are no Kalahari Bushmen with spectacles. It just doesn't

01:01:07.580 happen. This is amazing. This suggests that because my parents wore glasses, I should wear glasses is not true.

01:01:14.060 Or is there an epigenetic part of this? Well, both. There is a genetic component. And if you look at

01:01:20.700 siblings of individuals who wear spectacles, there is a higher incidence of myopia or hyperopia.

01:01:28.620 But that could be susceptibility, right? It could be susceptibility.

01:01:31.260 And then the environmental trigger is what's going to do it in anyone?

01:01:34.460 And we don't know whether parents of reading children were reading children themselves. So

01:01:42.700 it's hard to separate out the genetic component. But there does seem to be a genetic component as

01:01:48.220 well. But the environmental component seems to be way stronger and more powerful. So if you take

01:01:55.500 parents who don't wear spectacles and you put their child in a dark room and give them an electronic

01:02:01.980 device or a book or whatever it is and have that child focus it near for hours on end, odds are

01:02:09.580 they're much more at risk for developing nearsightedness.

01:02:12.780 So when I just think about this through the lens of my kids. So my wife has perfect vision. I don't.

01:02:18.300 What is my diopter? I think I'm minus three and minus four.

01:02:22.940 That's about right.

01:02:23.580 Yeah.

01:02:23.900 So what does that mean in terms of the 20 scale? I'm 20.

01:02:26.540 You're probably like, it depends on how much you squint and look at the eye chart. We honestly don't

01:02:31.580 really attach a lot of significance to the 2100 or 2080, whatever it is. You're probably

01:02:38.460 in that ballpark 2100 maybe. But I'm clearly at the point where

01:02:42.300 without contacts, I can't drive. I can't do anything. I mean, I know some people who

01:02:47.740 are minus 15, they literally can't, they have to put glasses near the bedside.

01:02:53.180 I'll spend the first hour of the day without contact lenses.

01:02:55.340 That's right. Because you could probably, you know, things are very well.

01:02:57.900 It's easier for me to read without my contacts.

01:02:59.660 Very, things for you are very well in focus at a typical normal reading distance.

01:03:03.980 So your eyes have been tuned like postnatally for near work. That's in your development and

01:03:13.820 you must've spent a lot of time reading or doing near tasks.

01:03:16.380 Well, that's the thing I was thinking about. I was like, I grew up in Canada. So from a light

01:03:19.500 perspective, it wasn't so great. You had two months of no light whatsoever. But I didn't watch TV

01:03:25.180 much as a kid, maybe 30 minutes a day. I was mostly outdoors. So I don't know how much of it,

01:03:31.980 but I also didn't, I'll tell you, this is funny. I didn't need my first pair of glasses till college.

01:03:39.020 So it could also be that this happened later in my life as a result of more book work.

01:03:44.780 For sure. So the classic example is we see law students who have great vision when they enter

01:03:50.700 law school and then they read for 12 hours a day. And then they come in and they say,

01:03:55.180 you know, I think my vision's going. And you look at them and sure enough,

01:03:59.100 they've become nearsighted. And that's not rare in, in many graduate school situations where there's

01:04:03.980 just, just, you know, grinding reading for hours on end.

01:04:07.740 So when I think about our kids, cause now I just think, well, what, what can I,

01:04:12.220 it's too late for me. Right. But, but so get them outside. So they are. So fortunately they live

01:04:17.260 outside, but when they're inside, they're obsessed with like playing with Legos and trains and trucks.

01:04:24.300 And I mean, that's near, right? So is it, is it that, Hey, that's, there's nothing wrong with that,

01:04:29.260 but you just have to make sure they're spending a couple hours outside a day.

01:04:31.820 I think the data would suggest that good illumination would be helpful

01:04:35.340 as opposed to poor illumination. But you know, you don't want to discourage near activities

01:04:41.820 because those are really important development. That was the flip true. So you mentioned that

01:04:46.860 hunter gatherers or illiterate societies who are out by definition outside all the time,

01:04:52.940 there's no such thing as nearsightedness in them. Do they develop farsightedness?

01:04:56.780 Not really. I think that they are fairly well tuned if we want to use that term to distance vision,

01:05:04.700 to prey hunting and things like that. So distance vision is, is very well tuned. Now there's a whole

01:05:11.740 host of other problems that come into play. Once you've outlived your genetic usefulness,

01:05:17.420 you've reproduced and you've imparted your knowledge onto the next generation. You can go

01:05:21.740 ahead and get cataracts because you're done genetically useful. Your utility.

01:05:25.900 So the cataract is sort of like atherosclerosis if functionally, which is it really,

01:05:30.540 it's the one thing that really has no bearing on your reproductive capacity, 0.65

01:05:34.220 but is otherwise inevitable to our species. It seems to be fairly inevitable to our species.

01:05:40.300 And I've, as I mentioned earlier, I just haven't seen patients in their seventies,

01:05:44.940 typically that don't have some cataract formation. Now there are patients who are 80

01:05:49.420 that are still functioning with cataracts, but the optical clarity of their lenses has degraded to the

01:05:56.380 point that it's not the way it was when they were 20. Maybe their visual needs are significantly

01:06:03.500 reduced at that age. But if you took an 80 year old lens and you'd put it in a 20 year old person,

01:06:09.500 they would be shocked at how poor their vision is. That's really interesting. Now, earlier you

01:06:13.820 mentioned that we think that senescent cells or at least the soluble secretory products of senescent

01:06:20.380 cells are probably playing a role in this. Well, I think in the lens, it's mostly that

01:06:26.060 the lens proteins are degrading or becoming damaged over time, maybe with UV light, because we know

01:06:33.740 light exposure is certainly related to cataract formation as are some of the other things that

01:06:38.780 I mentioned, like glucose going into the lens, corticosteroid use. We don't know what it is

01:06:45.500 specifically about trauma that causes a premature loss of clarity of the lens proteins.

01:06:52.860 The trauma ones got me worried because I boxed for so long. I took out way too many hits to the

01:06:59.100 head. I hope that doesn't come back to, I mean, I've already been, I'm worried about that for other

01:07:03.340 reasons. Let's put it this way. The cataract would be the easiest thing to fix. Yeah, yeah, yeah.

01:07:07.500 You know, that's, you know, cataract surgery today is like a four or five minute procedure and it's

01:07:13.100 astonishingly effective. How often does one need to repeat that surgery?

01:07:17.900 Cataract surgery typically is not repeated. It's a once in a lifetime deal.

01:07:21.900 And what you're noticing is like you're wearing glasses that are dirty. Is that effectively what

01:07:25.660 the patient with cataract is experiencing? I think the first thing they notice is probably

01:07:30.540 changes in their night vision, glare, halos, streaks off of lights at night,

01:07:36.540 problems with contrast sensitivity for those who can appreciate that loss of contrast.

01:07:43.100 Those are really early signs of cataract formation.

01:07:46.060 So then the patient comes to you, they're 74 years old, or let's say it's sooner. They're

01:07:50.620 70 years old. More like 64 or 54. Yeah.

01:07:53.660 Okay. And you're telling them, hey, Billy, you've got cataracts. We're going to just ride this out

01:07:59.260 until you tell me you've had enough. Typically we let the patient decide when it's the right time for

01:08:04.140 them to have the surgery. Once we determine that the cataract is visually significant,

01:08:09.500 there are people who elect to have their cataracts removed earlier than they really

01:08:15.980 need them removed as a means of getting rid of their glasses prescription. Because now the lenses,

01:08:21.900 the implant lenses that we put in to replace the cataract have advanced in function to the point

01:08:28.940 that they can fix the near vision as well as the distance vision as the astigmatism, the nearsightedness,

01:08:34.700 the farsightedness, the presbyopia, all those things that we've been talking about, they're all

01:08:39.100 correctable with artificial lenses that we put in the eye to replace the cataract.

01:08:44.300 Wow. But earlier when you talked about during your residency, one of the pieces of bread and

01:08:49.260 butter of your practice would have been cataract surgery. That didn't involve intraocular lenses.

01:08:54.540 No, it did. It did. And there's a fascinating history about the evolution of intraocular lenses.

01:09:01.180 But back in those days, the implant lenses that were put in were simply designed

01:09:07.660 to give the patient good vision with spectacles, just to replace the cloudy lens with something that

01:09:15.500 was in the ballpark of good distance vision. Sorry, I need to take a step back because I'm actually

01:09:20.940 kind of confused. Does all cataract surgery involve the placement of an extra lens?

01:09:27.260 Yes, that's correct. There are exceptions to nitpickers who will listen to this, but

01:09:33.580 virtually every cataract surgery that we perform involves the removal of the cataract and replacing

01:09:41.660 it with an artificial lens. Again, you'll have to pardon my ignorance. Does that mean removing the

01:09:45.340 entire lens or removing a diseased part of the lens that has a cataract?

01:09:49.020 Remember our analogy of the M&M candy? Yes.

01:09:51.340 So we leave, we- You leave the shell?

01:09:54.140 Right. We open a hole in the front of the shell. We take out all the chocolate and then we,

01:09:58.780 now we have kind of like a flattened bowl, looks like a Japanese tea pot, flattened. And we put the

01:10:05.100 implant lens in that bowl and that holds the implant in place. 0.95

01:10:09.740 And is it a viscous fluid that gets hardened or is it a hard object that goes directly in?

01:10:16.300 It's actually a bendable plastic object. And the bendability of it-

01:10:20.780 Is what allows it to get in.

01:10:21.980 It allows us to fold it up and put it through a tiny incision and then it opens up.

01:10:28.060 So that was a very big advancement.

01:10:30.140 When did that happen?

01:10:31.020 1980s was when that began to become-

01:10:35.500 What happened before this?

01:10:36.460 So this is a really amazing series of stories, but I'll abbreviate them in the interest of time. But

01:10:43.580 in the ancient world, if you had cataracts, the way they dealt with it is that they would just

01:10:49.260 poke the lens of the eye backward and it would drop down into the bottom of the eye

01:10:55.020 so that you now had a clear optical pathway, again, to let light in. And this took someone

01:11:01.420 who was functionally blind and allowed them to see shapes. So that was better than-

01:11:07.260 Right. Because you don't have a lens. So there's no way you can focus.

01:11:09.900 You can't focus. All you can see are shapes.

01:11:11.820 But it's basically like taking someone who has no light transmission and saying,

01:11:16.220 we're going to let unfocused light go through.

01:11:18.220 Right. So some light's better than no light. So that's what happened in Hammurabi time.

01:11:24.540 I'm always amazed. We look at that now and we say, that's barbaric.

01:11:27.980 Yeah.

01:11:28.300 The fact that they knew enough to do that is kind of amazing.

01:11:31.900 Well, they probably tried everything else first.

01:11:33.580 And presumably they did some, they probably dissected

01:11:36.620 cadaveric lenses and tried to figure this out, I would assume.

01:11:39.900 And there've been artifacts uncovered that I think a lot of them were made out of gold,

01:11:44.700 but they would take a gold needle and poke it through the cornea. And then it was called

01:11:51.660 couching the procedure. They would just poke the lens and it would detach from its ligamentous

01:11:57.820 attachments and then drop down into the bottom of the cavity of the eye. And you see some of these

01:12:02.460 artifacts from Egypt. This was done in China. It was certainly done in ancient Greece. That was how

01:12:08.940 you dealt with cataracts back then. By the way, it's just worth pausing for a moment to reflect.

01:12:12.940 Like, so we're, if you're talking about the pharaohs, you're talking about what 5,000 years

01:12:16.460 ago, right? This is not in an evolutionary timescale. That's a, that's a pittance, right?

01:12:20.140 My profession is an old one. And you think like,

01:12:23.500 it would be better to be the poorest person on earth today than to be the pharaoh of Egypt 5,000 0.68

01:12:29.260 years ago. Yeah, I think in many ways.

01:12:30.940 You know, or certainly it would be better to be in the bottom 10 percentile economically today than the

01:12:36.060 top 10 percentile 5,000 years ago. If the best you have to your cataracts is some guy sticking a hot

01:12:43.100 poker in your eye. That's right. So then you fast forward to right after World War II and there's an

01:12:51.020 ophthalmologist in the UK named Harold Ridley. And he notices that some of the RAF fighters would have

01:13:01.740 fragments of their canopy, their plexiglass canopy shatter when they were fired upon.

01:13:07.900 And these things would actually get inside the eyeballs. Shards of plexiglass essentially would

01:13:13.180 be inside the eyeball. And the dilemma was, well, what do we do with this? And he learned very early

01:13:18.940 on that these fragments were biologically inert. That the eye was perfectly happy and people could

01:13:26.380 walk around the rest of their lives with plexiglass inside their eyeball. And that's a shard of sharp

01:13:32.460 plexiglass. And this is in part because the lens is so immune privileged.

01:13:37.180 Well, this is a foreign object that has now entered the eye, not necessarily in the human

01:13:42.380 lens. It might even be in the vitreous cavity or in the front of the eye.

01:13:46.380 So there was something about sharp plexiglass that didn't-

01:13:48.940 But it's something about plexiglass. So the light bulb goes off that, wait, you can put

01:13:53.900 plexiglass, which is essentially polymethyl methacrylate. You can put that in the eye and

01:13:59.340 the body doesn't really care that it's there, doesn't mount an immune response.

01:14:04.860 So in Ridley's book, which I've read, it's really amazing. But some intern asked him,

01:14:11.580 well, when you take this cataract out, are you going to replace it with a new lens? And he looked

01:14:17.100 at this young intern in a very British fashion, I'm assuming, and just said, you know, that's the 1.00

01:14:21.900 stupidest question I've ever heard. And then he went home and thought, wait a minute, that's 1.00

01:14:25.980 brilliant. We should replace it. And then they lathed a lens from some spectacle maker that was

01:14:33.660 about the size and shape of the human lens. And they actually threw eight of these in patients.

01:14:41.980 And there's amazing footage of, I think one of the first operations,

01:14:46.060 they dropped the lens on the floor. And of course, it's the only one they had.

01:14:50.300 So they pick it up and rinse it off. And they, it's fine. They put it in. And these patients did

01:15:00.060 like shockingly well. And this was viewed as heresy. And there was, you know, 20 years of

01:15:08.140 you're blinding people. And, but eventually the technology won out and it became.

01:15:13.500 So there were bad outcomes, presumably.

01:15:15.820 I think in the early days, for sure, there must've been for sure. And there were,

01:15:19.740 but like any new technology, the first iteration of it is probably

01:15:23.660 terrible and maybe just a little bit less terrible than the alternative.

01:15:28.300 And now it's a ubiquitously used.

01:15:31.020 So that's, I never thought, because basically I didn't realize until you said it, that

01:15:35.020 polymethylmethacrylate is all over the body in terms of joints. Like when you replace a knee joint,

01:15:40.140 the tibial plateau, I think is made out of polymethylmethacrylate. So presumably there's

01:15:44.220 something about it that is just invisible to the immune system.

01:15:47.420 Well, we don't, and we don't use that material anymore because it's stiff. It is not deformable.

01:15:53.340 So you had to, you had to, in the old days, you had to make a fairly large incision to get the cat.

01:15:59.100 To get this thing in.

01:15:59.900 First of all, to get the cataract out and then to get the implant lens in.

01:16:04.060 Again, two converging technologies made that go away. The number one was,

01:16:09.900 we were able to take the cataract out through a tiny incision.

01:16:13.340 Because you break it in situ?

01:16:15.500 We break it up. We emulsify it essentially with ultrasound,

01:16:19.500 or now we even sometimes use a femtosecond laser to break up parts of it. But the bottom line is that

01:16:24.860 we can remove the cataract through about a two something millimeter incision, which is very small,

01:16:30.540 like the thickness of a pencil lead, basically. And we can now take these implant lenses and fold

01:16:37.820 them up and put them through that same tiny incision. And then they can open up and be

01:16:43.580 exactly where you want them to be. Now, why is it important for the incision to be small?

01:16:48.460 Well, if you make a big incision, obviously it takes longer to heal, but it induces astigmatism.

01:16:54.540 So you want the incision to be tiny.

01:16:57.660 So does the, using your M&M analogy, does the coating on the surface of the M&M grow back?

01:17:04.300 No, it does not.

01:17:05.500 So it's fixed. Whatever hole you put in there, they're stuck with.

01:17:08.780 Yeah, it's fixed. Now, sometimes the coating, the M&M candy shell can begin to opacify after

01:17:17.500 surgery. And we can treat that in the office with a laser where we can just disrupt that coating.

01:17:22.860 So this has got to be like, my mom, actually my mom's 72nd birthday is today. I don't know if

01:17:28.780 she's had any issues with cataracts, but if not, she's due for them. My dad has,

01:17:34.940 he's 83. I'm trying to think, he must've had surgery then by now, right? There's no way.

01:17:39.660 Odds are. Yeah, odds are.

01:17:40.700 So I can't believe I've never really talked about this with him, but is it, it must be a game changer

01:17:45.020 for a patient to come out of the clinic or the OR whenever that, wherever these, do you do this in

01:17:50.540 your, well, you have an OR in your office. We do, but cataract surgery, we do in an

01:17:54.460 ambulatory surgery center. But you know, it may be that your dad didn't talk about it because it was

01:17:58.940 such a non-event. You know, you go in for cataract surgery and the next day you're kind of back to your

01:18:03.660 regular activities. Right, but wouldn't it have been a big event in terms of his ability to see?

01:18:07.260 For sure. Especially now that the implant lenses can correct the near vision and the distance

01:18:12.780 vision. So that in addition to the added clarity from just removing the cataract, they, patients

01:18:20.060 typically have this benefit of not needing. So this is a procedure we should all be looking forward to

01:18:25.080 when it comes. Like you're going to get. I don't know if I would go that far. I mean,

01:18:28.940 it's still surgery. There are risks associated with it. What are the biggest risks? No, I think that

01:18:33.420 the number one thing we think about is infection, but it's extraordinarily unusual to see an infection,

01:18:39.660 less, less than one in 10,000 cases where you'll see a serious infection. It's like any other surgery

01:18:46.680 in the body. You look for bleeding damage to the inside of the eye. You have to keep tabs on the

01:18:51.840 pressure. It's basically everything that you would look for. If you were taking out an appendix,

01:18:56.620 you're also dealing with in the eye. What fraction of patients do not have a material

01:19:04.300 improvement in their vision or have some deterioration of even another subset of vision? So

01:19:08.840 yes, you've taken away my cataract. I can see better in the sense of clarity, but oh my God,

01:19:15.600 I became abjectly nearsighted as a result of it. Yeah. I think that's pretty unusual because the

01:19:22.360 science behind getting the prescription correct or very close to correct is pretty advanced.

01:19:28.920 And tell me what that entails. So if I came in and right now and I had a cataract,

01:19:32.660 what are you assessing microscopically to make it? So I'm getting the impression not everybody gets the

01:19:38.320 same lens. No, they do not. And some of these lenses are expensive. So, and they involve the

01:19:44.300 patient having to pay some extra money to get it. And more money gets you what?

01:19:48.160 I mean, I think the more money people pay, the more spectacle independence they get in terms of

01:19:54.720 optical quality, all the lenses are. How much does a lens cost? Or pair, I guess,

01:20:00.680 since you're doing both. I mean, I'm the wrong person to ask. Honestly, I don't even know.

01:20:06.400 But directionally, like if somebody has to pay out a pocket for one of these.

01:20:09.360 If they're getting just like regular cataract surgery and there is no attempt to get rid of

01:20:14.740 spectacles, it's probably going to be completely covered by their health insurance.

01:20:18.360 And if they're saying, I want to go premium all the way, get rid of my glass.

01:20:21.700 It could be thousands of dollars out of pocket. If they want to get rid of all their spectacle

01:20:26.100 dependence. And what patients will tell us is they'll say, well, what else do I use every waking

01:20:32.940 moment of my life forever? They could go on a vacation for a week or two and spend that money

01:20:38.680 and then the vacation is over. But we find that patients value, as we pointed out earlier,

01:20:43.700 their vision, they value it pretty highly. And their independence, I think, is really what they're

01:20:49.000 trying to preserve.

01:20:50.800 This is amazing. I had no idea that when, look at how much I didn't know. I didn't know you were,

01:20:54.640 I literally, this is how dumb I am. I thought cataract surgery is literally removing the sort of 0.96

01:21:00.800 crud that's in the lens. And I don't know, I just naively assumed it would, like the good stuff

01:21:06.120 would grow back. I never knew you were putting another lens in, let alone that you could actually

01:21:11.220 use the new lens as a way to correct other visual defects.

01:21:16.580 That's right. And the technology has evolved to the point where you can actually correct those

01:21:22.660 spectacle requirements. Now, many of our patients don't really care about spectacle independence.

01:21:27.640 They just want to see well, and that's easy to achieve as well. But as these lenses have gotten

01:21:34.380 better, our capabilities have gotten better.

01:21:38.420 If I needed cataract surgery today, knowing my diopter, the minus four, minus three business with

01:21:44.460 the slightest stigmatism, although I still haven't figured out how that's impacting my vision,

01:21:49.020 I guess I sort of have it just, but we'll come back to that. If you were going to swap out my

01:21:53.140 lens, would you be able to correct the deficit of my magnitude?

01:21:56.980 We could. Yes. Yeah. Now, you know, the problem with a lot of these

01:22:01.340 eyes is they are attached quite firmly to people. And sometimes the patient's set of expectations

01:22:12.540 can be unrealistic in terms of what we can deliver. And so we have to really carefully

01:22:17.480 educate them on, well, what can these lenses actually do? Am I going to see like a perfect

01:22:23.160 hunter at dusk while still being able to read up close? And maybe the answer is yes. Maybe the

01:22:32.200 answer is no. And can you tune it? Like, for example, if I said, Stephen, look, I don't care

01:22:36.720 if I have to keep wearing contacts. I would love to not have to wear reading glasses. Because if I'm

01:22:41.920 going to be honest with you, the reading glasses are a way bigger pain in my butt than contacts. 0.92

01:22:47.360 Because I just put my contacts in in the morning and take them out at night. It really doesn't 0.80

01:22:50.480 phase me. The reading glasses annoy the hell out of me because I never remember to bring them to

01:22:54.820 restaurants ever. So I'm shining a phone light at my menu and putting it out here and, or I'll be

01:23:01.500 reading the book to my kid at night. And I'm like, oh, hang on, buddy. I got to go get my glasses.

01:23:05.940 Like, that's actually more of an imposition of my life. Yeah. It's not an unusual request where we

01:23:11.660 can intentionally set your vision for near or leave it for near. You can certainly do that. It's just an

01:23:17.620 optical calculation to set the point of focus where you want it to be. You asked earlier about,

01:23:25.440 well, what happens if I come into the clinic? What gets measured? Well, one of the first things

01:23:30.420 that we have to do is make sure that the surface of the cornea is tuned up from a dry eye standpoint,

01:23:37.000 because those dry eye patients, the surface of their corneas, it's not optically pristine. It's

01:23:44.220 a little distorted. Do contact lenses make that better or worse? It makes it a lot worse. And it

01:23:48.700 can throw off our measurements, which can throw off our calculations because it's kind of pretty

01:23:54.520 simple Newtonian physics, right? If you know the length of the eyeball and you know the curvature

01:24:00.600 of the front of the eye, and you know the index of refraction of the stuff that's inside the eyeball,

01:24:06.940 how bendy the material is, light bendy the material is, you can correct for, as long as you know

01:24:13.780 where the implant lens is going to reside, you can correct for placing that image on the retina.

01:24:20.640 So the more perfect the shape of the cornea, the better that calculation is.

01:24:25.620 That's right. And that is probably the weak link in the set of measurements that we take,

01:24:29.920 because we can measure the length of the eye from front to back very accurately with lasers. So we can

01:24:35.840 sort of, it's almost like a sonar, but with light, we can bounce a beam off of the back of the retina,

01:24:42.080 and we know exactly how long the retina, how long the eyeball is. And we know roughly where the

01:24:48.380 implant lens is going to rest when we put it in. And if we know some other dimensions of the eye

01:24:55.660 and use the front curvature as a, as one of our pieces of data, we can predict what power implant

01:25:02.380 lens to put in. Wow. Okay. So is there anything left on the IOL front or is there another huge step

01:25:12.620 function of technology that's going to be coming there? Cause it doesn't, I, it already sounds

01:25:16.500 pretty remarkable. Well, I, in the mid two thousands, I started getting involved in product

01:25:23.640 design for a type of implant lens that could actually zoom focus front to back, not a bifocal

01:25:32.960 or a trifocal where you had different zones of focus, but a lens that could actually move or change

01:25:39.420 its shape. And I developed an implant that we put in humans in multiple clinical trials outside the

01:25:48.560 United States. And we found that we could zoom focus kind of like the human lens would,

01:25:55.840 but the multifocals, which are the lenses we've been talking about that like bifocals,

01:26:01.820 trifocal implants surpassed the capability of what we could achieve with the lenses that I designed.

01:26:08.900 And until someone comes out with a focusing implant lens that can zoom focus with the same degree of

01:26:18.220 power as the bifocal and trifocal implants, it's not going to be successful. But if we had a lens that

01:26:25.760 could change its shape or change its position and zoom focus seamlessly from near to far, that would be a

01:26:34.240 game changer. I assume that there's no, you don't take like the lens from a young person who's passed

01:26:40.660 away and ever try to implant that into, it doesn't work the way a cornea does. That's right. That's

01:26:47.920 right. In fact, if you violate that capsule of the lens, the lens immediately becomes cloudy. So here's

01:26:55.420 an example. Let's say that you talk about trauma. So a typical scenario is somebody is working with a

01:27:02.980 weed eater or whatever, a weed whacker. Yeah. And a shard of rock or glass or something goes through

01:27:10.340 the cornea and embeds itself in the lens. And it might even be an optically unimportant part of the

01:27:17.160 lens. Maybe it's off to the side, but once that capsule has been pierced, inevitably lens protein

01:27:24.180 starts leaking out. Inflammatory cells become- Yeah. You violated the privileged site.

01:27:29.840 It's no longer privileged. And within days you start to see a cataract.

01:27:34.240 And they need a new lens.

01:27:35.300 They need a new lens for sure. Do they need a new cornea by the way? 0.98

01:27:38.260 Well, they sometimes do, but oddly enough, sometimes an object will pass through the

01:27:42.960 cornea and because it's traveling at such a high velocity, it's usually sterile and it'll go through

01:27:49.600 the cornea and embed itself in the lens or the iris or wherever. And some of these objects can be

01:27:56.080 left alone. But if the cornea has been damaged sufficiently that it's no longer able to

01:28:02.260 transmit a clear image, then it has to be replaced.

01:28:06.060 Wow. So let's talk a little bit about corneal pathology. So everyone's probably heard about

01:28:10.960 corneal abrasions. That's a very important reason. It's one of the few things I remember,

01:28:14.800 right? In surgery, you always tape the patient's eyes shut because you don't want an eyelid flipping

01:28:21.420 open in the middle of surgery and nobody's paying attention and a drape is running over the eye and

01:28:26.020 scraping the cornea. Is that the biggest insult that we think about for the cornea?

01:28:31.840 I mean, that's probably one of the more common ones. If you think about that eye that's being left

01:28:37.360 open in surgery while a patient is asleep and not blinking, that's sort of the extreme version of dry eye

01:28:44.420 where the cornea has completely dried out. And even if you didn't abrade the cornea,

01:28:50.500 those epithelial cells would be so damaged by exposure just by not being continuously bathed in

01:28:58.240 tears that they would be severely damaged. So dry eye is intimately related to corneal abrasion

01:29:08.860 because you lack the lubrication that normally takes place to prevent that type of thing.

01:29:14.080 And how much of an issue is that in our society?

01:29:17.220 Dry eye? Yeah.

01:29:17.880 Oh, it's enormous. I mean, if you think about the things that cause dry eye-

01:29:23.940 I mean, there's obviously lots of medications that do it through anticholinergic side effects.

01:29:27.900 Absolutely. But think about all the antihistamines. Hormonal influences are

01:29:32.000 profound in terms of dry eye. Anything that causes dry mouth can also cause dry eye. In that sense,

01:29:39.060 autoimmune conditions can cause dry eye. So Sjogren's, rheumatoid arthritis,

01:29:43.340 all of the connective tissue diseases have a dry eye component to them.

01:29:48.800 Perturbations of thyroid metabolism cause dry eye. But a lot of women suffer from dry eye because 0.54

01:29:57.040 they're, I think it's mostly the influence of honestly, a lack of testosterone that is probably

01:30:02.240 most intimately linked to dry eye. But we see women on hormone replacement therapy that have 0.99

01:30:08.240 miserable dry eye. So you think the addition of estrogen and progesterone post-menopause could

01:30:13.620 be an issue? Or do you think it's still just the lack of testosterone that you-

01:30:16.420 I think it's the lack of testosterone.

01:30:17.720 Why do you think that?

01:30:18.680 I think it has to do with the health of the epithelial cells on the conjunctiva. But there

01:30:25.480 may be also influences on the secretion of tears from the lacrimal gland as well. But dry eye is,

01:30:32.600 I mean, it's, I don't want to say it's universal in patients who are over a certain age, but it's

01:30:38.440 extremely common.

01:30:39.580 What type of eye drops should we be using? How do we apply them?

01:30:43.720 Well, it really depends on the type of dry eye that you have, believe it or not. Because there

01:30:47.920 are, we think of tears as just salt water, but that's really not what it is. It's really an

01:30:54.160 emulsion of lipids and mucin and all sorts of immune modulators and antibodies and all sorts of

01:31:04.120 things in this soup. Some of it is just what we refer to as the aqueous component of tears,

01:31:09.200 really just the salt water. But the sebaceous glands that are in the eyelids, we call them

01:31:15.600 meibomian glands at the little, where the lashes come out of the skin, the secretions of those

01:31:21.620 meibomian glands can become dysfunctional. And that means that the tears have a hard time gliding

01:31:28.840 over the surface of the cornea, and that can lead to dry eye. So all sorts of things that cause

01:31:36.800 meibomian gland dysfunction. Some of that relates to diet. And some people believe that a diet high

01:31:44.820 in saturated fats is more likely to cause meibomian gland dysfunction. Certainly colder weather,

01:31:52.520 like the sebaceous glands in your skin, respond better to sunlight, to heat. In a cold environment,

01:31:59.400 those can become plugged up and bacteria can build up along the eyelid margin, causing inflammation.

01:32:08.000 And when there's inflammation, the lacrimal gland shuts down even more. So dry eye is really multi,

01:32:15.100 it's got a number of different causes. Now, when I think about eye drops, I think about sort of the

01:32:20.140 dropper that you try to get in your eye and you can never get it. At least I can never get it in my eye

01:32:24.480 because I end up blinking all the time. So then I, you try and drop it into your-

01:32:29.040 Into the corner, yeah.

01:32:29.900 The corner and then let it sit down. But then I've also seen like the mist, right? So tell me

01:32:34.580 about the different ways that one even applies these.

01:32:36.440 Yeah, I think those are really the main ones. I mean, eye drops work pretty well for most people,

01:32:41.340 but there are some mist sprays that, believe it or not, you can spray some of these. There's one

01:32:47.260 hypochlorous acid compound that you spray on the lids and it sort of migrates into the eye and

01:32:54.380 actually is very good for reducing the bacterial counts at the lid margin, which is part of that

01:33:01.280 inflammation cycle that is so critical in dry eye. But most artificial tears come in the form of an

01:33:07.680 eye drop.

01:33:08.440 And that's okay.

01:33:09.080 That's fine.

01:33:09.740 And it's okay if you can't manage to keep your eye open or should you force it and hold your eye

01:33:14.180 open?

01:33:14.400 I mean, it's, you gotta, at some point you gotta get it in the eyeball, but that's one of just a

01:33:19.460 whole bunch of strategies that we use for treating dry eye. We add artificial tears, but we think that

01:33:26.680 there's a very significant benefit from supplementing with omega-3 fatty acids, especially high doses of

01:33:33.360 omega-3 fatty acids and omega-6, certain types of omega-6.

01:33:37.580 Yeah, which omega-6 is it again?

01:33:39.020 That's what you'd find in black currant seed oil or borage oil or evening primrose oil. That's the

01:33:44.640 GLA, gamma linoleic acid. So that, that is very helpful in dry eye. And interestingly, there was a very

01:33:52.860 large randomized clinical trial looking at omega-3 supplementation in pretty high doses.

01:34:00.860 Do you remember how high?

01:34:02.360 Three grams.

01:34:03.420 Wow.

01:34:03.820 Of actual-

01:34:05.560 Of EPA, NDHA.

01:34:06.600 Correct. Yes. And the placebo arm was olive oil, which is presumed not to have a benefit in dry eye.

01:34:13.540 And it showed no superiority of omega-3 compared to olive oil. However, you know,

01:34:21.580 there's been a lot of criticism of this study. It's called the DREAM study. It was put on by the

01:34:26.620 National Eye Institute. It turns out that if you bring people into the eye doctor four times a year,

01:34:33.440 everybody gets better. You know, their compliance with artificial tears gets better.

01:34:38.080 And were they using artificial tears?

01:34:39.340 They were. They were able to use whatever they would normally use to treat their dry eye.

01:34:43.540 So I, I guess like in the same way that if you go to the dentist four times a year,

01:34:47.700 all of a sudden you're flossing before you go to the dentist, both arms of the study got better.

01:34:53.940 But it's our, it is our very strong clinical impression that omega-3s in high doses help

01:34:59.380 with dry eye, primarily from, I think, an anti-inflammatory standpoint.

01:35:03.200 Let's go back to light for a minute. So I've got some friends who are so fanatical about the

01:35:10.980 importance of light that they never wear sunglasses. And I'm, I'm kind of, there's a part of me that

01:35:16.680 thinks light is, wow, it's got to be really important. I think about, you know, all the time

01:35:20.420 I get outside in the light, it's great. It's great. But I also like wearing sunglasses because

01:35:24.500 there's a part of me that's sort of afraid that too much UV light is damaging. So what's the balance of

01:35:30.740 sunglasses versus not? And I want to talk about polarized glasses or they, do they matter and all

01:35:36.540 that kind of stuff? Yeah. I mean, clearly there's a dose related phenomenon here. You know, too much

01:35:41.620 light is bad. Too little light is bad. What's the right amount? I tend to recommend sunglasses for

01:35:48.380 our patients. Let's start with just the most obvious one, the most common site of skin cancer,

01:35:55.020 the lower lid, lots of basal cells, squamous cell carcinomas. Sunglasses certainly reduce the

01:36:02.640 incidence of that. Then we look at the photo aging of the lens itself. I think it's not a bad thing to

01:36:09.860 delay the onset of cataract. And then the retina, macular degeneration. I think there's pretty clear

01:36:17.120 evidence that UV exposure, particularly of the magnitude that you can get outside, is associated

01:36:23.580 with an elevated risk of age-related macular degeneration. Now, do we see this in hunter

01:36:29.660 gatherers who have otherwise amazing habits and therefore tend to be relatively privileged from 1.00

01:36:35.720 optical pathology? Yeah. So the confounding variable there is that Northern European ancestry is a risk

01:36:42.860 factor for macular degeneration, probably because of the lack of pigment. Because that pigment is protecting

01:36:49.540 that very vulnerable vascularized component of the back of the eye. Oh, wait. So the darker your eye,

01:36:56.320 the more protected you are? Absolutely. In the same way that your skin is more protected with more

01:37:00.740 melanin. So light-eyed patients have more light getting in from the front of the eye. So their iris

01:37:08.960 literally blocks less light hitting the lens. Yes. And the retina has less pigment behind it.

01:37:14.560 And so the vascular supply to the retina is more exposed to UV light. And that's the way it's

01:37:20.900 evolved because they've been in environments that don't have as much light available.

01:37:24.840 But if you live near the equator or your ancestry is from that area, then you're going to have more

01:37:29.780 pigment from an evolutionary standpoint. But I understand the fanaticism about wanting to have

01:37:37.180 lots of blue light or bright light. But I think that it probably is fanaticism. I don't think that,

01:37:44.420 you know, at least if your goal is to reproduce, teach your children until they're 15 and then die,

01:37:51.100 then get all the light you want. But if your goal is longevity or the postponement of senescence,

01:37:57.780 certainly ocular senescence, I think it makes sense to protect your eyes from UV light.

01:38:01.880 So for example, like let's, so you, you came over here today where it's middle of the day in Austin.

01:38:06.660 It's a typical Austin, beautiful, sunny day. You're driving with sunglasses.

01:38:10.680 Oh, for sure. Absolutely. A hundred percent.

01:38:13.340 Okay. You're in sunglasses when you're outside after what time in the morning?

01:38:18.960 If I'm outside and the, and my vision is better with sunglasses, you know, it's not worse with

01:38:25.760 sunglasses than I'm going to wear sunglasses. I don't wear them at night and I don't wear them,

01:38:30.100 you know, if it's very early in the morning, but if conditions allow, I'm going to wear them.

01:38:35.820 We talk about with sunscreen, the importance of you're still susceptible to sunburn in the clouds,

01:38:41.220 right? If you're at the beach all day and it's kind of an overcast day, you can still,

01:38:44.360 do you recommend people still wear sunglasses, even if it's not a clear blue day?

01:38:48.120 For sure. And sometimes, you know, this kind of came up during the recent eclipse because,

01:38:53.540 you know, people were saying, okay, I'll look at the eclipse. This one was a few years ago.

01:38:58.200 So I'll just use sunglasses. Well, that's actually much, much, much, much worse because you're

01:39:04.340 increasing the aperture of your pupil because everything is dim, but you're letting through

01:39:10.420 all this very damaging light. Because no amount of sunglasses could block a straight shot looking

01:39:16.380 at the sun. Correct. So I think even on a cloudy day, I do recommend that people wear sunglasses.

01:39:22.720 Okay. What are polarized glasses doing?

01:39:24.820 You know, as you know, you know, polarized lenses are essentially, it's, it's, it's a lens that has

01:39:30.360 a bunch of lines drawn in it all in the same direction so that some of the light is blocked,

01:39:35.340 but in one meridian, all the light effectively is let through, but perpendicular to that, none of

01:39:41.700 the light gets through and polarized lenses have some pluses and minuses. One of the big minuses I found

01:39:49.100 is that a lot of the displays in your cars now, you get this really messed up cross polarized effect

01:39:58.840 where the light coming off of the screen is polarized. And if you look at it through polarized glasses,

01:40:05.020 if you tilt your head, it gets brighter and darker.

01:40:08.080 You can actually not see it at some time.

01:40:08.920 You cannot see it. And by the same token, many of the windows or winds, I don't know if it's the

01:40:15.880 windshield or the side windows, but I've noticed wearing polarized lenses, which I only wear for

01:40:21.380 fly fishing now that I would get these very weird effects by tilting my head because of the cross

01:40:28.520 polarized effect. Essentially you have two different polarized filters and it's letting through variable

01:40:34.480 amounts of light bending, depending upon the orientation of your head and your eye and the,

01:40:38.600 and the spectacles.

01:40:40.060 I have found myself more comfortable in non-polarized lenses unless I'm on water.

01:40:44.120 Yeah. I think, and then the issue there is that the light bouncing off the water or theoretically a

01:40:50.020 highway, it's all pretty much, a lot of it is polarized in one direction. That's the rationale behind

01:40:55.580 polarized lenses. And for seeing a fish, if you're a fly fisherman, for sure, that's helpful.

01:41:00.920 I fly fished for the first time last month and I could see getting into that. That is an art.

01:41:08.060 For sure it is. But in terms of polarization, there's no evidence that I've seen that polarization

01:41:15.780 versus non-polarization in sunglasses helps. It's really the UV filter that is helpful for what we're

01:41:24.900 doing in terms of protection of eye health. You could wear clear spectacles as long as they had

01:41:30.480 UV protection and still achieve the benefit of sunglasses.

01:41:35.480 Yeah. That's an important point, right?

01:41:37.520 It's not the tint.

01:41:38.580 It's not the tint.

01:41:39.300 It's the ultraviolet protection.

01:41:40.640 And it's the same as true in a car, right?

01:41:42.480 That's right.

01:41:42.740 I mean, the glass of the car is, assuming you don't have tinted windows,

01:41:45.880 is still getting rid of most of the UV light.

01:41:48.260 Most of the UV, but not all. So you will see, and dermatologists tell us this,

01:41:53.040 that in truck drivers who are in North America, they see more UV damage to the left side of their

01:41:59.860 face than the right side of their face by far. And in the UK, it's exactly the opposite.

01:42:05.600 So even car and truck windows let some UV light in.

01:42:09.780 Okay. So let's now go back to the standard situation of nearsightedness. So person comes

01:42:16.380 in, they're nearsighted. Decision one is I'm going to correct this with glasses versus contacts.

01:42:22.640 We'll start to talk about corrective surgery in a moment. Do you nudge people one way or the other?

01:42:27.400 I mean, I wore glasses for the first four years that I needed corrective lenses. So that meant

01:42:35.680 basically college. I'm trying to think in med school. I think by med school, I was wearing

01:42:40.520 contacts. By residency, I went back to glasses because the call, you just couldn't be predictable

01:42:48.200 about when you were going to put them in. So I did all of residency in glasses. And then since that

01:42:52.680 time, I've been a hundred percent contacts. Yeah. It's funny because we'll see residents

01:42:56.640 or fellows or whatever, and they come in and on their one day off and they're seeing one of our

01:43:02.080 optometrists. And when did you last have your contacts out? And they're like, I think it was

01:43:07.500 June 30th, right before my internship started four months ago, you know, that sort of thing.

01:43:13.860 And so, as you know, residents are notoriously bad about their own health hygiene because you're so

01:43:21.300 busy. But to answer your question more directly, I don't really see patients for regular eye exams myself.

01:43:29.360 So the people who see me are seeking surgery already. But in terms of, hey, I'm at a cocktail

01:43:37.340 party and someone says, should I wear glasses or contact lenses or spectacles? Like, well,

01:43:42.380 you know, the safest thing you can do is wear spectacles for sure.

01:43:46.280 Wait, do you use glasses and spectacles interchangeably?

01:43:48.820 Yes. When I say spectacles, I'm referring to glasses to distinguish them from stuff you drink

01:43:55.680 water out of. So, yeah. Spectacles is the term of art for glasses.

01:44:05.880 Yeah. Yeah. You were thinking it's some sort of exotic type of nose-mounted spectacle.

01:44:09.600 Yes. I was like, oh, there must be glasses, but then there's a spectacle.

01:44:13.240 It's like down at ye olde spectacle shoppy.

01:44:17.360 Something like that.

01:44:18.120 Anytime my wife talks about pushing the gas pedal, I'm like throttle. 0.75

01:44:21.600 It's a throttle.

01:44:22.500 It's a throttle application.

01:44:23.800 We need some gas. No, we need petrol. Okay.

01:44:27.060 Right.

01:44:27.680 It's gasoline or petrol. It's not gas. Gas refers to natural gas. When you push that thing,

01:44:33.040 it's throttle application. Yes. Okay. No.

01:44:34.820 Yeah. We're hard to live with, aren't we?

01:44:36.060 Yes. Yes.

01:44:36.800 Okay. So, spectacles and glasses are synonymous. That's the safest thing you can do. They're going

01:44:42.980 to work every time and there's essentially no risk associated with them. There's a big debate about

01:44:49.660 what the next safest thing is. Is it contact lens wear for 10 years where you might be susceptible

01:44:56.280 to infection or is it laser vision correction? But I tend to say if you're doing fine with

01:45:03.340 spectacles or contact lenses, do that.

01:45:06.420 I was kind of hoping you were going to tell me get laser eye surgery because there's a part of me

01:45:11.980 that just wants to do it for the sake of doing it and getting rid of contacts once and for all.

01:45:15.640 But you were very much in the camp of, you asked me a bunch of questions. And at the end,

01:45:20.420 your conclusion was, these don't seem to be an inconvenience for you. You've never once had

01:45:24.200 an eye infection. You tolerate them really well. They don't seem to bug you.

01:45:28.160 And you like your near vision.

01:45:29.760 Yeah.

01:45:30.320 Yeah. And so, if you were to correct your distance vision with laser vision correction

01:45:35.400 and set both of your eyes for distance, you would lose that near vision.

01:45:41.120 Until maybe I get my cataracts fixed.

01:45:43.100 That's right.

01:45:43.520 Then we can tweak them.

01:45:44.480 That's a whole other story.

01:45:46.660 So, let's talk about the advent of laser eye surgery. So, I think everybody listening to

01:45:50.520 this has heard of LASIK. Most people probably haven't heard of PRK, which we'll talk about.

01:45:56.300 When did... PRK came along first, I assume?

01:45:58.920 Yeah. A little bit earlier. Yes.

01:46:00.440 And that was when? In the 90s?

01:46:02.660 Right. So, the approvals for PRK and LASIK were in the mid-90s, 1995, 1996. The first procedures

01:46:10.480 were actually done in... The first procedure was PRK and it was done in New Orleans. And I happened

01:46:18.080 to be in training there in New Orleans. And this was performed by a physician called Marguerite

01:46:24.860 McDonald. And she did the very first treatment on a human eye. The way this came about was that

01:46:30.920 eczema lasers, which are the kind of lasers we use in LASIK and in PRK, which stands for

01:46:38.680 photorefractive keratectomy. Eczema lasers are and were used to etch microchips. And an engineer at

01:46:48.900 IBM realized that you could change the curvature or you could make cuts in human tissue. And because of

01:46:57.040 the nature of this ultraviolet laser, there was essentially no bystander trauma to the adjacent

01:47:03.940 tissue. So, the tissue could be etched or cut. And because it generated no heat, there was no

01:47:12.720 immune response generated typically so that these incisions or whatever it was, they would heal

01:47:19.340 without scarring. And I can remember vividly looking at the very first patients that were in

01:47:25.920 an FDA clinical trial that had PRK. And I was astonished that you could look at them under a

01:47:32.760 microscope and you could not detect that surgery had been done. That was really a revelation for me,

01:47:39.200 where I just saw these eyes that looked like normal eyes. And the only difference was the patients

01:47:43.420 could see. So, the first eyes were treated in 89 and then that led to FDA approval in 95.

01:47:51.860 And the treatment in 89 was part of clinical trials, I'm assuming.

01:47:54.500 For sure. It was part of a clinical trial.

01:47:55.900 So, let's explain what PRK does before LASIK.

01:47:59.240 Yeah. So, the way it works is that you have the cornea, again, like the glass on a watch,

01:48:05.460 the thing a contact lens would sit on. And let's say that the person is nearsighted. The cornea in that

01:48:12.500 person is a little bit too steep to focus the light perfectly on their retina. Another way of

01:48:20.580 looking at it is- And again, the cornea is about two millimeters thick?

01:48:23.480 No, it's about a half a millimeter thick. It's about 500 microns, maybe a little more.

01:48:28.820 So, either the cornea is a little too steep or the eyeball is a little too long,

01:48:34.680 probably a little of both. We can't change the length of the eye.

01:48:38.360 By the way, the length of the eye is the one that we talked about being somewhat malleable

01:48:41.660 during development. That's right.

01:48:43.500 And is the corneal shape hereditary? Is that the hereditary component of vision?

01:48:48.500 The corneal shape doesn't seem to change that much throughout life. It's the length of the eye

01:48:54.260 that changes, unless there's a pathological condition that changes the cornea. So,

01:48:59.580 since we can't change the length of the eye, what we can change is the curvature of the front of the

01:49:04.980 eye. And if you think about it, you don't have to change the curvature that much. Think about how

01:49:10.260 thin a contact lens is.

01:49:12.100 How thin is it? I mean, I know I can feel it, but I don't know what that is. Is that also about

01:49:15.880 half a mil?

01:49:16.920 No, it's less. I honestly don't know. I don't work in that world, but it's pretty thin. I mean,

01:49:23.520 it's like a little piece of cellophane if you think about like an AccuView disposable.

01:49:27.140 Yeah, it probably just feels thicker because of all the goo on it.

01:49:29.780 Yeah. So, I'm sure someone will correct me and say, you should know how thick a contact lens is. I

01:49:35.240 don't. But it's thin, right? It's pretty thin. So, it's just that little curvature that needs to

01:49:41.860 change in order to focus the light on the retina.

01:49:45.140 And just to use an extreme example. So, you take somebody who has a very minimal

01:49:49.300 degree of nearsightedness. So, let's say their diopter is minus one. And then you contrast the

01:49:56.120 lens that they would wear to the lens that someone who's near blind at like a minus 10.

01:50:01.580 10. Is the minus one creating more of a bend or less of a bend? Meaning, is it a bigger curve or

01:50:07.840 a smaller curve?

01:50:08.740 So, the person who's minus one, their cornea is less potent in bending light than the minus 10

01:50:16.360 person is. That minus 10 means their eye is 10 units too strong. And we need to reduce the power

01:50:26.040 of the eye. So, how would you fix that with a laser? Well, first of all, how do you fix that

01:50:30.160 with the contact? So, their lens has to look- The curvature of their lens has to be effectively

01:50:37.360 flatter than their eyeball. So, you need a larger radius of curvature or a flatter eye.

01:50:43.080 I got it. Okay. So, you would actually build up the outside of the lens.

01:50:45.960 Exactly right. Okay.

01:50:47.240 So, it's even easier to explain with laser vision correction. So, let's take a crude analogy,

01:50:53.140 which is that the cornea is made out of wood and I have some sandpaper. Well, I can sand down

01:51:00.220 the center of the wooden cornea and make it flatter. To take the point off. 0.87

01:51:04.100 And I'm removing some sawdust goes away. Now, that is flatter. And so, it's less powerful in

01:51:10.780 bending the light and I can focus that on the retina. So, in your minus one example,

01:51:16.080 we would remove about 20 microns of tissue. That's not a lot. You figure a human hair is about 50

01:51:23.960 microns. So, like less than half of one human hair's thickness. And PRK does that directly?

01:51:31.660 With an eczema laser on the very front part of the cornea. So, the way we do it is that

01:51:39.040 the very front coating of the cornea is called the epithelium. It's a very thin layer, kind of like-

01:51:45.940 How thick is the epithelium there?

01:51:47.560 It's about, again, about 50 microns, something like that. 50, 55 microns. So,

01:51:53.800 it's got a basement membrane. But it's about, call it 50 microns. So, we remove that layer of cells

01:52:01.200 with, the way I do it is with a solution of some eye drops of alcohol. And it just sloughs right off

01:52:08.040 and it grows back.

01:52:09.360 Just like isopropyl alcohol?

01:52:10.780 Yeah. You could use that or ethanol.

01:52:12.640 You've anesthetized the eye before doing that, obviously.

01:52:15.000 That's a practice builder, yeah. Thank you for that tip.

01:52:19.580 How do we get the repeat business?

01:52:20.920 I don't know why no one's coming back.

01:52:22.540 Why don't we numb the eye first? That'd be really good, yeah. So, you anesthetize the eye

01:52:26.060 and then you put some alcohol solution on the front of the cornea. You remove that epithelial

01:52:32.420 layer, which is going to grow back in the same configuration. And then you use a very carefully

01:52:38.920 calibrated laser to change the shape of the cornea.

01:52:41.840 Yeah. Again, dumb question. The laser's coming at what angle? 0.99

01:52:46.020 It's essentially effectively perpendicular to the cornea. So, the patient's laying down

01:52:49.920 flat. They're on their back.

01:52:51.280 And you put something in to wire their eyes open?

01:52:53.200 We're holding their lid apart for them.

01:52:54.700 Are they sedated?

01:52:54.900 They're, I mean, I honestly give people Valium because it's just sort of an intimidating

01:52:59.780 minute. You know, it only takes a minute.

01:53:02.940 Here's what my fear would be in doing it is like my desire to blink would be so overwhelming. I'd

01:53:08.440 break the little eye barrier. Of course, I wouldn't, but I'd end up moving my head and

01:53:12.280 you'd zap the wrong part of my eye and I'd be blind.

01:53:14.500 Everyone, that's everyone's fear. You know, it turns out Valium is undefeated.

01:53:20.880 It's just a question of how much. It's a very good drug. But to address what you, you brought

01:53:27.620 up several things there. First is a lot of patients fear that they'll do something to

01:53:32.500 goof up the surgery. And there are a number of reasons why that really can't happen. But let's

01:53:40.100 go through the procedure from the beginning. Long before this patient ever laid down on this

01:53:47.320 gurney to have this laser treatment done, their eye was digitally mapped using what we refer to

01:53:55.120 as a wavefront sensing device. So think about this. We send in a very narrow beam of light with a laser

01:54:04.640 and we look at how it bounces back from the cornea. It bounces back in a distorted fashion.

01:54:10.100 So we send an ideal ray of light in or multiple rays of light in and they bounce back in a

01:54:17.260 distorted fashion. The amount of that distortion allows us to map.

01:54:22.740 So you do a topo map.

01:54:24.100 It's much more than a topographical map. It's the entire optical pathway of the eye from the

01:54:29.980 retina to the back, all the way to the back and front. So we look at the entire distortion pathway. 0.99

01:54:36.560 And there's more than one way to do this, by the way, there is a topography based way to do this as

01:54:41.520 well, which is very effective. But the one I'm describing to you is sort of the easiest one to

01:54:47.340 think of. We send in a known uniform beam of light and look at how it bounces back from the back of the

01:54:56.360 eye. That tells us what are the distortions present in this eye? How much nearsightedness,

01:55:02.120 how much farsightedness, but also all of these physics terms of-

01:55:06.700 We didn't do this in me, right? You only do this in someone who's going to be a candidate?

01:55:09.660 We may have done it in you just for grins, but we diagnostically, this is part of our workup for

01:55:15.680 laser vision correction. And we look at how this particular eyeball, Peter Atiyah's right eye,

01:55:22.580 distorts light as it goes through the optical pathway. This technology was developed for

01:55:30.240 telescopes that have to contend with atmospheric distortion. So the way this works is that

01:55:38.180 telescopes, and I'm talking about like Keck, the best ones in the world, they send up

01:55:44.380 a diagnostic laser into the atmosphere. And the distortion that that laser is encountering

01:55:52.320 is adjusted for in real time with a deformable mirror, a very thin mirror. And that allows them

01:56:02.060 to essentially correct for the distortions of the atmosphere in real time. And those are constantly

01:56:07.540 changing. We have the benefit of not having to deal with real time evolving distortion, but we can

01:56:14.840 take a snapshot of what are the distortions of Peter's right eye. And then we can build them into

01:56:21.820 the laser vision correction that we do on Peter's right eye. Part of doing that means that we have

01:56:28.680 to be able to track your eye. So we have to lock onto and register your eye with the equipment. And

01:56:37.260 any movement that you make, part of your fear was, I'm going to mess it up. Well, the laser can track

01:56:43.500 far more rapidly than you can move your eye.

01:56:46.760 So while you're doing this, patients' eyes can be moving.

01:56:49.800 They can.

01:56:50.680 And it doesn't matter because the laser is moving.

01:56:52.420 I mean, it's sort of annoying when they, you know, so we tell, we coach them,

01:56:56.260 hey, look at the flashing light. But that's really just to keep them in the ballpark of

01:57:00.520 where the tracker can lock onto them.

01:57:02.940 I like knowing I'm not the only one that has this ridiculous fear of blinding himself.

01:57:08.400 First of all, it's not a ridiculous fear. Secondly, it's universal. When I say to patients,

01:57:14.020 hey, I'm not going to let you do anything to mess this up, they're like, thank you. Thank you for

01:57:19.980 saying that. That was the thing I was worried about because you don't want someone to laser

01:57:23.760 your eye and you looked off to the side. Oh, disaster.

01:57:28.700 Not only are you blind, we also gave you a brain tumor. 0.99

01:57:31.100 That's right. So the laser will not fire unless you are within its range of tracking and it will

01:57:39.520 move faster than you can move.

01:57:42.020 So PRK is, I like your analogy, basically changing the shape of this via the mechanism of like,

01:57:50.080 it's not sanding it off, but it is.

01:57:51.900 It's vaporizing the tissue.

01:57:53.020 It's vaporizing the tissue.

01:57:54.140 And it's a laser that's sort of scanning around the cornea where it does a little treatment here.

01:57:59.460 And then we know thermally that we don't want to do another shot right next to that one. So we

01:58:05.240 move over here and we want to let the tissue cool down for a few milliseconds. And then we go over

01:58:11.040 here. So the laser dances around.

01:58:12.980 And how many minutes approximately does it take? Does it take longer the worse the prescription is?

01:58:17.540 Yeah, for sure.

01:58:17.740 So you have more to shave.

01:58:18.600 So like minus two, it might be 15 seconds.

01:58:22.400 That's it?

01:58:22.940 Yeah.

01:58:23.560 So minus 10 would be how long?

01:58:25.600 Like a minute or so. It depends on the laser. It depends on the overall treatment size,

01:58:30.560 how much astigmatism.

01:58:31.760 Oh, you're fixing the astigmatism as well.

01:58:33.720 And all the little distortions, how much coma, trefoil. These are physics terms that

01:58:40.500 I didn't really think I would become fluent in, but all these little optical distortions that

01:58:47.020 optical physicists are very familiar with, we measure and do our very best to eliminate with

01:58:54.220 laser vision correction.

01:58:55.660 So the whole procedure is what, half an hour by the time you'd put this thing in the eye,

01:59:00.680 put this thing in the eye, give them their Valium?

01:59:02.960 For PRK, two or three minutes plus the Valium time.

01:59:07.000 So take your Valium an hour before.

01:59:08.780 Or maybe it's, yeah, it's like half an hour. We have them chew it up and then it works pretty

01:59:12.440 quickly.

01:59:13.660 Okay. So talk about the recovery from PRK, because one of the things I remember you saying

01:59:19.480 when I was sort of humming and hawing about this was the biggest drawback of PRK is the

01:59:26.840 recovery takes longer. But you otherwise, I think, really talked about PRK as the gold

01:59:31.540 standard.

01:59:32.540 The only reason I might've said gold standard was that it came first. It was the first

01:59:37.360 procedure. And if you look at PRK and LASIK, which we'll get to in a bit, if you look at

01:59:44.520 those procedures, say 30 days later, they're indistinguishable in terms of results, but the

01:59:52.020 LASIK patients get there way quicker. So PRK, now I've removed your epithelium. So now you

01:59:58.220 have this, let's say it's a seven or eight millimeter diameter area of your central cornea

02:00:04.680 that has no epithelium. It has to grow back.

02:00:07.820 That's like having a big corneal abrasion, essentially. Luckily we have drugs, drops that

02:00:15.800 can reduce the feeling of the foreign body sensation dramatically. So we put those drops

02:00:21.960 on the cornea, put a contact lens over the eye, like a bandaid. It's really like a, like

02:00:27.320 a regular soft contact lens. And then the epithelium begins to heal from the outside in.

02:00:34.280 That takes 30 days?

02:00:35.800 No, that takes about four days. But here's the thing. It's like if you were to have a

02:00:41.940 cut on your arm, it would heal over, but you'd still be able to detect where that cut was because

02:00:47.220 those cells have not fully remodeled themselves. So the cut heals over or the defect in the

02:00:54.300 epithelium heals over in about four days, maybe less.

02:00:57.520 And then you take the contact lens off?

02:00:58.980 You can take the contact lens off then, but the vision is still not perfect yet because those

02:01:04.440 cells have to reorient themselves like a bunch of orderly bricks in a brick wall. And when the

02:01:12.500 cells first cover that defect, it's a very thin sort of disorganized layer of cells that have

02:01:19.860 accomplished their mission of sealing the defect and preventing you from being susceptible to infection,

02:01:26.040 which is their job, to quickly cover the defect. But then the body can turn its attention to

02:01:31.640 reorganizing those cells in a more-

02:01:33.760 So you do one eye at a time, obviously.

02:01:35.520 Not with PRK or LASIK, no.

02:01:38.140 Because the level of vision, typically we do both eyes on the same day because the level of vision

02:01:45.580 is probably about 2030 or 2040 within a day or two. So when I say the vision, the visual recovery takes a

02:01:54.960 while, you get pretty good pretty quickly, but that last little bit takes several days. So you

02:02:03.960 probably could drive a couple, maybe two, three days later, but you wouldn't have 2020 vision at that

02:02:11.240 point. So LASIK, the only thing I know about that is there's a flap involved.

02:02:17.180 That's right.

02:02:17.500 So presumably you're not shaving off the epithelium, you're cutting a flap, and how much of that

02:02:24.760 tissue you take off determines the shape of the new cornea when the flap comes back?

02:02:30.880 Right. So the laser that does the vision correction, all the little distortions,

02:02:36.260 the nearsightedness, the astigmatism, that's all the same laser. So that part of the procedure is

02:02:42.200 identical. But instead of doing that on the surface of the eye, now we're using a step before that,

02:02:49.940 where we create a flap in the cornea using a different type of laser. So we use a femtosecond

02:02:57.680 laser to create about a, let's say a hundred micron flap. So we are now under the epithelium.

02:03:04.940 So you've taken 20% of the cornea up?

02:03:07.760 That's right. About 20% of the cornea up. And now think of it as in our analogy where we were

02:03:15.040 sanding a wooden eye before. Now think of the cornea as a book. And in PRK, I'm removing the

02:03:22.180 first 10 pages of the book. Now I open it to page 100 and I'm taking out 100 through 110. And then I

02:03:28.280 close the book. The beauty of LASIK is that because that tissue removal is sequestered under that flap,

02:03:34.740 the body doesn't perceive that anything has been done. So it's very typical for patients who have

02:03:40.480 LASIK to be 20-20 the next morning. And so that's the appeal of that procedure.

02:03:46.260 And that's why LASIK was developed post-PRK, presumably as a way to get around

02:03:50.800 the healing process of PRK?

02:03:53.180 Yeah. That was sort of a technological race and the way it developed was interesting. And some of it was

02:03:59.400 in pursuit of more rapid visual recovery.

02:04:03.280 So what percentage of corrective eye surgery in the United States today is PRK versus LASIK?

02:04:09.080 I think the lion's share is LASIK. 0.85

02:04:10.460 Yeah. I think it changes, but it's probably about 80% to 85% LASIK. And not to confuse things,

02:04:16.440 there's another procedure called SMILE, which is a very small, but perhaps growing segment of the market.

02:04:22.280 And we can talk about that in a sec, but the lion's share of it is LASIK. And there is a,

02:04:29.260 but a significant chunk of PRK.

02:04:31.280 Are there more risks in LASIK than PRK?

02:04:34.100 Well, the risks are different because the risks of infection with LASIK are lower because you don't

02:04:40.860 have this open-

02:04:41.160 You don't take the epithelium away.

02:04:42.080 That's right. But you introduce another step in the procedure where you now have a flap and that

02:04:49.020 flap can, you know, if it's not performed correctly, that can lead to problems. I think

02:04:55.260 there is a little bit more dry eye issue with LASIK compared to PRK as well, because when you create

02:05:03.320 that flap, the way tearing works is that a signal from the front of the eye goes to the lacrimal gland

02:05:11.500 which then secretes tears. If you create a flap, you temporarily sever some of the nerves that

02:05:19.560 are sending the signal. And eventually over time, those nerves typically regrow back and you reestablish

02:05:26.780 that feedback mechanism. But I think you get more dry eye with LASIK than with PRK and for longer.

02:05:35.600 That is a controversial statement. There are people who have data to show that they're equal,

02:05:41.760 but I think they both result in temporary dry eye in most patients. Some patients have dry eye for

02:05:48.380 really long periods of time after both procedures, but the majority of patients are kind of back to

02:05:53.880 their baseline in about probably 60 to 90 days.

02:05:58.040 What about night vision or low light vision?

02:06:00.720 So that's fascinating. In the early days of LASIK and PRK, the weakest part of vision was night

02:06:10.300 vision. And that was because the shape of the treatment that we did and the diameter that we

02:06:17.060 treated was limited. So we couldn't really treat the peripheral part of the cornea that comes into play

02:06:24.240 when your pupil gets big. So if you are treating a central part of the cornea that is smaller than a

02:06:31.900 big pupil at night, you're going to see halos from that untreated peripheral part of the cornea.

02:06:39.520 Over the last, like, I don't know, from the nineties to now, the treatment beam patterns have

02:06:47.060 changed to address that issue and to treat that peripheral cornea differently. So now night

02:06:54.200 vision complaints, we find to be pretty unusual with laser vision correction.

02:06:58.460 Is there a difference in the cost of these procedures?

02:07:00.840 For us, no, but I'm sure there are some surgeons who charge more for one than the other.

02:07:06.200 The added step of LASIK adds some cost, but PRK has more post-operative care, frankly,

02:07:14.320 because it requires more visits to see these folks, but we price them the same.

02:07:20.400 And how much does it cost, by the way? I mean, it's probably come down a lot in

02:07:24.060 20 years, right?

02:07:24.760 You know, I don't think that it has. I think it's been pretty stable. I think it's probably

02:07:29.700 about a couple thousand dollars per eye is about the average in North America that you'll find.

02:07:35.660 What are the exclusion criteria? Like, who is not a candidate for either one?

02:07:40.500 Yeah, there are certainly contraindications, some of them relative, but some of them are absolute.

02:07:45.860 I'll give you an absolute one. There are conditions of the cornea where the cornea is

02:07:51.100 biomechanically unstable, where the cornea is actually has a tendency to bow forward in a

02:07:58.140 pathological state. And that means that the cornea, it's a moving target, essentially. So

02:08:04.480 further biomechanically weakening the cornea makes no sense. And doing either procedure would

02:08:11.140 do that. There are patients who have irregularities in their astigmatism that cannot be measured or

02:08:18.780 corrected with any laser vision correction. There are patients that have certain autoimmune diseases

02:08:25.540 that maybe render them as poor candidates for laser vision.

02:08:29.580 Based on the risk of healing or?

02:08:32.400 Based on the risk of healing or perhaps just the overall health of the eye. And that sort of

02:08:38.040 extends to people who have other eye diseases like cataract or maybe glaucoma or retinal pathology.

02:08:45.580 You are typically operating on healthy eyes when you're doing laser vision correction. So if there's

02:08:50.960 some other issue involved, you might not be a candidate.

02:08:55.600 And is there anything that, like, well, I guess given the differences you've explained,

02:09:01.640 why are 15% of people still opting for PRK?

02:09:04.500 Well, there are certain patients where that's a far better option. So we talked about how you're

02:09:10.060 removing pages from a book. Well, what if you have a really deep treatment that you need to do,

02:09:15.200 and the book is sort of thin to start out with? Maybe it's better to begin on page one than to

02:09:20.580 begin on page 100.

02:09:21.980 So the stronger the diopter and the thinner the cornea, that might move you more towards PRK?

02:09:27.340 Sometimes the thickness of the cornea will dictate it. Sometimes it might be related to someone with

02:09:32.480 pre-existing dry eye, and we're thinking, well, we have data that these two procedures are about the

02:09:38.800 same in terms of dry eye, but our clinical impression is that LASIK makes them a little drier.

02:09:43.740 So maybe let's do PRK on this particular individual. There used to be some restrictions

02:09:51.300 in branches of the military.

02:09:53.720 Right. I remember that you couldn't have a flap in your eye if you were a pilot.

02:09:56.300 That all went away. So pretty much all the aviators and pilots can now have LASIK or PRK.

02:10:02.840 In fact, the military is one of the largest providers of laser vision correction now in

02:10:07.420 the United States. But there are a couple of holdout special forces branches where they don't

02:10:14.240 want you to be, I think, maybe an army ranger. And that has to do with getting poked in the eye

02:10:21.000 and the possibility that a flap could be damaged. And some of this is sort of vestigial

02:10:28.340 lore, and it's hard to change the military's rules.

02:10:32.700 Yeah. But they'll just say PRK or nothing.

02:10:34.480 Yeah. But I'd say that the overwhelming majority of the branches of service allow either treatment.

02:10:40.540 And certainly all the commercial airliners, they allow PRK or LASIK. But with the caveat that you

02:10:47.740 have to get to the point where you can pass the flight physical. And the same thing's true of

02:10:52.860 people who want to be pilots or aviators. If they need to have 2020 uncorrected vision to be a pilot,

02:10:59.400 they have to have 2020 vision after laser vision correction.

02:11:03.480 Is it pretty much a given that you can at least get someone to 2020 after laser corrected vision?

02:11:08.140 I mean, the way the lasers are built today, it's typically the case that you can get them

02:11:12.940 to 2020 or better than 2020, as we were describing before.

02:11:16.560 And if you take them to 2015 and they have presbyopia to begin with, does it get any worse?

02:11:23.300 Or is it just that now they're noticing it all the time because they never get a break from it?

02:11:28.680 They never get to take their glasses off, their spectacles, so to speak.

02:11:32.000 Well, if you nail it perfectly so that their prescription is 0.00, I think their distance

02:11:39.400 vision will be phenomenal and their near vision will be whatever it is based upon their age.

02:11:44.780 So if they're 50 years old, they're probably going to need some near correction, some spectacles for

02:11:50.900 reading. If they're 41, 2, 3, 4, maybe even 45, they may not need glasses for close-up.

02:11:59.700 And then you mentioned this smile procedure. I haven't heard of that. What is that?

02:12:02.980 Yeah. You know, it's an interesting procedure. It's using a single laser, a femtosecond laser.

02:12:09.760 And this is, I want to go back to the book analogy where we opened the book to page 100.

02:12:16.680 Well, imagine if you could somehow create a little tunnel down to page 100 and snatch out

02:12:23.960 pages 100 through 110 while keeping the incision really tiny and perform it through a very small

02:12:33.080 keyhole procedure. That procedure has gained some traction outside the US and in the US.

02:12:39.460 It seems to be an effective procedure.

02:12:42.640 What problem is it solving given how effective LASIK is?

02:12:47.060 I would say the problem it was designed to solve was dry eye. But I think the problem it

02:12:56.060 really solved, especially outside the United States, was needing two lasers versus one.

02:13:02.260 So maintaining and-

02:13:04.280 But you could do one with PRK.

02:13:05.840 You could do one with PRK. But then you have the prolonged recovery time. So the idea was,

02:13:13.200 could you get LASIK-like velocity of return of vision-

02:13:17.440 With a single laser.

02:13:18.140 With a single laser.

02:13:19.400 And maybe along the way, reduce dry eye.

02:13:20.980 There are pros and cons to SMILE. The technology is evolving. I have not seen any data that shows

02:13:28.960 that SMILE is in any way better than LASIK or even equal to LASIK, frankly. But it seems to be a

02:13:35.620 very good procedure.

02:13:36.540 Are you doing it as well?

02:13:37.740 I'm not performing SMILE and doesn't mean that I won't in the future. And there are a number of

02:13:43.640 competing second and third generation versions of SMILE that will come on board. And if one of

02:13:50.000 them ever rises to the point where I think it's better than what we're doing, we'll offer that.

02:13:55.000 We didn't talk about glaucoma, yet I know every time I go to an optometrist or even when I came

02:14:00.580 and saw you, is that the one where you blow the air at my eye?

02:14:04.800 Well, that's sort of a-

02:14:06.260 Well, that's just an intraocular pressure test.

02:14:07.780 That's a way of measuring the intraocular pressure that we don't use, but it has the

02:14:11.760 advantage of not requiring the patient to be touched with anything. So you can indent the

02:14:17.140 cornea with a known amount of force from an air puff and look at how it optically deforms.

02:14:23.240 The disadvantage to the air puff, and it's not really considered a, I don't think a gold

02:14:27.580 standard of measuring pressure, is that if you blink really quickly and squeeze, then you can

02:14:35.540 have a false reading with that type of air puff tonometry. And we typically don't use that.

02:14:41.000 So how do you measure intraocular pressure?

02:14:42.600 We measure it with two ways, both of which indent the cornea, physically indent the cornea.

02:14:48.440 So that's why you anesthetize the-

02:14:49.960 After you anesthetize the eye with a known amount of force, and then you look at the amount of force

02:14:54.820 required to cause a certain amount of indentation.

02:14:58.460 And what's the definition of glaucoma?

02:15:00.000 Well, the glaucoma is probably about a hundred different diseases, honestly, but they all share

02:15:06.320 the final common pathway of damage to the optic nerve, the nerve in the back of the eyes,

02:15:12.240 the cranial nerve that you mentioned at the beginning, that is somehow related to pressure.

02:15:17.540 So a pressure-related optic neuropathy. Now, what's odd about glaucoma is that there are people

02:15:24.240 who have totally normal pressures with relation to the population, but that pressure is too high

02:15:29.880 for them, and they can develop damage to their optic nerve.

02:15:33.760 And the symptoms of glaucoma, are they all the- I mean, is it always some change in vision?

02:15:39.560 Is that what would bring someone to attention if they weren't getting a screening test?

02:15:43.200 It's funny, you just sort of like triggered a memory of mine. I had a patient, I was in training

02:15:48.260 years ago, and I was explaining to a patient that, you know, glaucoma is totally, has no symptoms at

02:15:54.660 all. You wouldn't notice it at all. And yet, if we don't find it, it could be really bad. And the

02:16:01.220 patient said, well, if it has no symptoms, what do I care? You know, like, what's the point? And what

02:16:05.500 I should have said was it has no symptoms until the very end. So what happens is that your peripheral

02:16:11.700 vision is damaged. And most people will not detect a slight reduction in their peripheral vision,

02:16:18.600 particularly if it's segmental. There's just one little area off to the side that they can't see,

02:16:23.900 particularly if the other eye is covering for that area. But as glaucoma progresses,

02:16:30.080 it can affect central vision, and then it becomes symptomatic.

02:16:33.900 How much of a problem is this in the United States, first of all, and then in the rest of the

02:16:38.160 world? Well, luckily, glaucoma has become much more treatable. So the pharmacological management

02:16:43.780 of glaucoma has gotten way better. And there are numerous laser procedures that can treat glaucoma

02:16:51.180 and what are referred to as minimally invasive glaucoma procedure, or it stands for MIGS,

02:16:59.220 minimally invasive. Basically, the management of this has gotten way, way better.

02:17:04.400 What's the 80-20 of this? 80% of them are caused by what, basically?

02:17:10.300 Yeah. So 80% of them are caused by what we refer to as garden variety chronic open angle glaucoma,

02:17:18.640 which means that the glaucoma is not a function of the anatomy of the front of the eye being too

02:17:24.820 crowded where the fluid can't get out. It's more a problem of overproduction of fluid inside the eye,

02:17:32.000 and the pressure is too high inside the eye as a result.

02:17:34.800 The vitreous fluid?

02:17:35.600 No, it's the aqueous fluid.

02:17:37.100 And what causes that? Is that endocrine? Is that, do we not know?

02:17:41.920 We do not know. I think this has a multifactorial pathogenesis. There are certainly family history

02:17:50.440 components to this where we see it run throughout families, but it's not like inheriting.

02:17:55.260 Does this run in parallel with diseases like type 2 diabetes, or is it uncoupled completely?

02:18:00.320 No, not really. It's not really coupled with diabetes. There's some relationship to

02:18:05.040 hypertension, blood pressure, but ocular hypertension, we refer to, eye pressure being

02:18:11.700 too high. You see it in patients who are not hypertensive at all.

02:18:16.480 Wow. The lifelong incidence is what?

02:18:19.580 I think you got me there. I honestly don't know, but it's-

02:18:23.500 Common or uncommon?

02:18:23.880 It's very common. Every eye surgeon sees glaucoma patients daily, multiple glaucoma patients daily.

02:18:31.100 So presumably, like any neuropathy, if you catch it early enough, it's fully reversible.

02:18:38.100 And if you catch it too late, you damage it? Because this is a central nerve, not a peripheral nerve.

02:18:44.760 Yeah. I think you can arrest the progression, but I don't think you can undo the damage that

02:18:50.720 has occurred. So once there's been optic nerve damage-

02:18:53.360 So it's not like sciatica?

02:18:54.880 No, I don't think so. I think once there's been damage, we expect that damage to remain.

02:18:59.940 So it's not unusual for a patient to have what we refer to as a visual field defect. So a little

02:19:06.680 area missing from their field of vision. And our goal becomes to prevent that defect from getting

02:19:14.040 any bigger. And you can typically do that once you identify it.

02:19:17.840 At what age does it start to become enough of a concern that we should be screening for it?

02:19:22.020 Yeah. I mean, I think everybody, when they go to the eye doctor for a yearly exam,

02:19:25.680 gets screened for glaucoma. The appearance of the optic nerve is examined as well as the pressure.

02:19:31.920 And those are probably the two most important things to look for with glaucoma.

02:19:34.720 So if you're screening annually, you're-

02:19:37.060 You're being checked for it.

02:19:38.020 You're in good shape.

02:19:38.560 Yeah. You're being checked for it. The incidence does go up with age. So in the 50s,

02:19:45.160 it's much more important to pay attention to glaucoma and beyond.

02:19:49.180 And presumably in the developing world where people aren't going to get eye care,

02:19:52.040 or even in the United States, if people don't choose to get eye care or can't afford to get

02:19:55.720 eye care, it's a bigger risk because they'll only present when they have symptoms.

02:19:59.800 That's right. That's exactly right.

02:20:02.000 All right. So to summarize, again, we think about kind of the longevity of the eye as a pretty

02:20:09.940 important thing, right? If you want to figure out a way to live to a hundred, we spend a lot of time

02:20:14.560 thinking about, well, you've got to really, really delay the onset of atherosclerosis. You have to

02:20:19.000 have a very aggressive strategy around the mitigation of cancer, Alzheimer's disease,

02:20:22.300 and all of these things. But it's these other things, teeth, ears, and eyes that I don't think

02:20:28.460 get enough attention, right? I mean, it's, you don't want to get to be a hundred and have no teeth

02:20:31.980 and you don't want to get to be a hundred and be deaf and you don't want to get to be a hundred and

02:20:34.720 be blind. Yeah. Those all sound bad. Yeah. So I mean, the things I'm picking up, unfortunately

02:20:40.640 for many of us listening to this, we can't go back and change what we did as kids. We can certainly

02:20:45.980 make a change in our kids so we can make sure that they are outside in natural sunlight. I don't put

02:20:51.940 sunglasses on my kids. Should I be doing that? Yeah. I mean, probably, you know, it's trying to

02:20:57.540 get a kid to wear sunglasses is tough. We've got to come up with better toys. Like my kids love

02:21:02.700 trains. So if I could figure out a way to tell them that wearing sunglasses was train-like,

02:21:08.140 this would be good. Yeah. It's tough. I mean, you see kids who are snow skiing, for example,

02:21:14.980 and they should be wearing goggles because those have built-in UV protection. So that typically works

02:21:21.700 for that type of thing. But gosh, when they're water skiing, they certainly can't wear glasses.

02:21:26.360 If they're swimming, they can't wear sunglasses. Although goggles these days are pretty good.

02:21:31.280 That's true. Yeah. That's hard to get my kids to wear goggles. But, you know, there's a certain

02:21:37.880 amount of just UV exposure I don't think it's possible to avoid. So the trade-off is when in

02:21:44.760 doubt, keep them out. Yeah. You know, hats are important as well. We didn't really talk about

02:21:49.120 that. That's a very good and effective way, but it's not enough because a certain amount of light

02:21:54.260 bounces off and hits the bottom of your cheek and goes right into your eye.

02:21:58.460 So for those of us that are now adults, basically we've kind of cast our lot with respect to that

02:22:04.720 malleable period of changing the length. Well, you know, we didn't really talk about like what

02:22:09.920 nutritional supplements might have some effect. And it's interesting because we know that with

02:22:15.280 cataract, that vitamin C deficiency is associated with an elevated risk of cataract, but it's been

02:22:22.580 shown really conclusively that vitamin C supplementation to supranormal levels does not

02:22:28.040 protect against cataract formation. And the things that have been looked at, I know A, C, and E,

02:22:34.440 basically antioxidants have been looked at. They've had no effect on cataract formation.

02:22:39.660 There is a little bit of mixed weak evidence for lutein and zeaxanthin as possibly being protective

02:22:47.100 for cataract. Also antioxidants, right? Yes, that's correct. And macular degeneration,

02:22:53.400 we didn't really touch on that very much, but that's a huge problem. You may have seen in the

02:22:59.500 drugstore, they sell ARIDS, A-R-E-D-S formula for macular degeneration. That stands for the age-related

02:23:07.800 eye disease study. That was again, a National Eye Institute initiative. And first they looked at

02:23:16.460 CE and beta carotene with zinc and a little copper. I guess they put the copper in because they were

02:23:21.840 worried about copper deficiency with zinc supplementation. And then they got concerned

02:23:27.960 about beta carotene. So they did another study where they took beta carotene out and put in

02:23:33.220 lutein and zeaxanthin, powerful antioxidants. And what they showed was that you could delay or reduce

02:23:42.440 the conversion of mild macular degeneration to severe, but it had no effect on severe disease.

02:23:50.820 And it also interestingly had no effect on people who didn't have macular degeneration. It didn't

02:23:56.100 prevent them from going on to get it. But I think most of us believe that there's something there.

02:24:00.720 There's some signal embedded in that noise. Is light also a big risk for macular degeneration?

02:24:05.740 It is. It is. So again, it's this dose thing. We want enough light so you don't become nearsighted,

02:24:12.160 but not so much that you're frying your retinas and giving yourselves cataracts. But I do think

02:24:19.020 that some form of broad spectrum antioxidant protection makes sense.

02:24:25.060 We didn't really talk explicitly about screen use.

02:24:28.420 Yeah.

02:24:29.120 I mean, you talked about it a little bit in that study in Asia where,

02:24:32.140 but I don't know if that was specific to screen use or just could have been just as much reading

02:24:36.980 or playing with Tinker Toys.

02:24:39.220 Yeah. It wasn't specific to screen use.

02:24:41.020 So what do we know about phones specifically and computers?

02:24:43.880 Yeah. So, you know, this is a super interesting, obviously topic and everything from people ask me

02:24:51.020 about blue blocking glasses. They ask about, am I damaging my eyes? Am I going to get macular

02:24:57.020 degeneration because I'm looking at a computer screen for 10 hours a day? I'll start with

02:25:01.620 the easy ones. The amount of UV radiation coming off of screens is sufficiently low that there

02:25:09.860 has been no evidence at all that it's going to cause macular degeneration in the same way that

02:25:15.500 you can't get a sunburn from a screen. I mean, the amount of blue light that you get from going

02:25:20.440 outside is many, many, many orders of magnitude greater than what you can get from screens.

02:25:26.140 But I do think that blue light can mess up your circadian rhythm. And, you know, it's,

02:25:34.080 if you take someone and expose them to blue light at noon, that's great. If you expose them to that

02:25:40.080 at 11 PM and then you try to go to sleep, that's messed up. And it's almost like we're running this

02:25:45.100 gigantic experiment with humans where they think about like you have a turtle. Let's say you take

02:25:53.620 a species of turtle that spends 90% of its time in the water, 10% on land. And we take that and flip

02:26:00.800 it. Now it's 10% in the water. And then we look at these turtles and we think there's something weird

02:26:07.200 going on with these turtles. Yes, they're surviving, but we've got them in a very altered environment

02:26:13.100 compared to what they were evolved to deal with. So giving people blue light from a screen that's

02:26:19.000 bright at 10 PM, 11 PM, and then asking them to go to sleep is a problem.

02:26:25.340 But there's not, it's not clear that it's damaging their eyes.

02:26:27.960 It's not damaging their retinas or they're giving them cataracts, but I think it's messing up

02:26:32.280 circadian rhythms. Although it is hard to disentangle that from the total amount of light that they're

02:26:41.040 seeing, which is also unnatural and what comes with it, which is the stimulation.

02:26:45.280 Right. You're thinking.

02:26:46.640 There seems to be a difference between watching TV and checking email before bed. Maybe neither are

02:26:51.880 ideal, but one seems demonstrably worse, at least for me.

02:26:55.600 Yeah. I think that's pretty universal. People feel that way that passive watching a TV is different

02:27:02.700 than I wonder where Winston Churchill is buried. You go down some wormhole and you're just seeking

02:27:09.980 information that takes you on these journeys. But one thing I do, I do have software embedded in

02:27:18.380 all of my PCs that changes the color temperature.

02:27:22.240 Like Flux or something like that.

02:27:23.140 I love Flux. And Flux is free, by the way, I think for end users. And it will take the blue

02:27:29.340 light sequentially out of your monitor as the day goes on, as the evening goes on to the point that

02:27:33.960 it's like super amber as you get ready to go to bed. I really think that's great.

02:27:39.980 Anything else we should be thinking about? I mean, the big takeaways for me have been

02:27:43.700 the importance of sunglasses, artificial tears, taking your contact lenses out as frequently as

02:27:49.980 possible, right? So don't sleep in them and stuff like that. I know it's not your field,

02:27:55.780 but do you have a point of view on daily versus the ones that, I mean, it just seems to me dailies,

02:28:00.120 if you can afford them, make more sense than the two-week ones that you have to wash every night?

02:28:04.740 Yeah. So, you know, I think the most important thing is that you just get them out of the eye.

02:28:09.600 We really don't like extended wear contact lenses. So whatever type of contact that is,

02:28:16.860 as eye surgeons, we tend to see a selected sample of patients who are the problems,

02:28:22.740 the people who have sight-threatening infections from sleeping typically in contact lenses.

02:28:28.280 So yes, I realize there are millions of people who sleep in their contacts and don't get

02:28:32.620 infections, but the people who end up in my office have had problems and some of them

02:28:39.060 quite devastating problems. So I'm not a big fan of, of sleeping in contact lenses in general,

02:28:45.620 but if you're going to sleep in contact lenses, I'd rather they be a perfect, pristine new pair

02:28:51.920 every single time and get them out as, as quickly as you possibly can.

02:28:56.560 Talked about eye protection. Again, I think we're a little more aware of that now than when we were kids.

02:29:01.380 The other takeaway for me is not to be so afraid of cataracts. They're inevitable and you can

02:29:06.980 actually, there's a, there's a, there's a potential silver lining, which is not only the improvement

02:29:11.780 of your vision, but potentially the correction of other age-related visual changes.

02:29:18.540 It is interesting that once word got out in the community that this was something that

02:29:23.460 could be done, you do see people coming in asking for cataract surgery, I think a little bit

02:29:29.540 sooner than they otherwise would because they know that this added benefit is a, is a potential

02:29:34.280 possibility. You know, in the old days when we did not have intraocular lenses or the generation, 0.91

02:29:41.020 a couple eye surgeons before me did not have intraocular lenses, you'd have to wear these,

02:29:46.600 what were called cataract glasses, these super thick lenses that were very, very powerful and

02:29:54.020 magnified everything and didn't really work all that well optically. So in that context,

02:29:59.180 wait, you wore those post cataract post cataract. Yeah. Cause there were no implant lenses and your

02:30:03.940 prescription was typically about a plus 10. So, you know, that a minus 10 is a very,

02:30:10.600 so there's very, these people can't see without these glasses. That's right. And so these are like

02:30:15.400 the Coke bottles. That's where glasses and spectacles meet. Do people even know what Coke bottles are

02:30:20.460 anymore? So the bottom of a Coke bottle is a really thick piece of glass and this would magnify your

02:30:25.880 eyes and make your eyeballs look enormous. And then you would have this all sorts of optical distortions

02:30:32.640 because it's very hard to make a super powerful magnifying glass with a long enough focal length

02:30:39.120 without peripheral distortion. And so you, in that context would put off cataract surgery as long as

02:30:46.840 humanly possible. So that's really not the case. Is cataract surgery one and done? I mean,

02:30:52.120 you said it is, it should be, but do people ever need re-operations? I mean, it's not unheard of

02:30:58.160 where someone will have an implant lens put in that isn't functioning the way it should. And that can

02:31:03.560 be replaced. Is it difficult to get the old lens out since you can't use the same technique to melt

02:31:08.560 it away? Not really. You can just fold it, pull it out or cut it in half. So it doesn't get,

02:31:13.740 cut it in half. It doesn't re-epithelialize or the candy coating of the M&M doesn't stick to the

02:31:18.240 new lens. A little bit, but you can free it up and take it out. You can swap out an implant lens.

02:31:24.140 It's something that we don't do it. It's not like changing your shirt, but you, you can certainly

02:31:29.840 do it. It's another operation. One other question I had on the laser surgery I forgot to ask was

02:31:34.640 how stable does your prescription need to be? Because if I understood correctly, again,

02:31:40.520 there's two things that are driving that, right? There's the length, which presumably that's the

02:31:44.900 part that needs to be stable. You don't want the length to be changing, but the shape of the cornea

02:31:49.460 you're actually fixing. So if there's anything that's changing there, do you care?

02:31:53.400 Well, there's really three variables. If you think about it, there's the cornea,

02:31:57.240 the retina, the length of the eye, I shouldn't say retina, but the length of the eye and the lens

02:32:04.140 itself. So we know that the lens is going to continue to change throughout life,

02:32:09.780 but typically not until you're in your fifties, sixties, seventies, when cataract formation will

02:32:15.680 start to affect the light bending power of, of the, of the lens, the cornea should not be changing.

02:32:23.540 So you just have to make sure this length is fixed.

02:32:26.280 That's right. And typically that, unless you're someone going back to law school or you're reading

02:32:31.040 30 hours a day, that is typically finished changing in the early twenties, like around 23, 24.

02:32:38.720 So does that mean our prescriptions shouldn't be worsening much as we age?

02:32:43.780 They really should not be worsening unless you're developing some cataract formation.

02:32:48.340 Okay. Yeah. I think mine have been stable for about 15 or 20 years. So that means I'd be safe to have

02:32:54.760 laser eye surgery from the standpoint of stability of prescription.

02:32:58.200 From the standpoint of stability of the prescription, that's right.

02:33:00.780 And then at some point in your future, and we tell patients this at some point, you're going to

02:33:05.460 start to develop some cataract formation and hopefully the boxing won't have any effect on

02:33:11.160 that UV exposure. You, you know, won't have any effect on that. Genetics will be in your favor.

02:33:17.700 And, you know, but if you're a, I didn't mention radiation is another, you know, we see people

02:33:23.960 who do fluoroscopy, like health professionals who are involved in exposed to ionizing radiation.

02:33:28.800 I mean, if you are the, if you're the tech working, you're the ship captain who smokes, uh, on a boat

02:33:36.220 that's carrying nuclear waste and you're diabetic, you're going to get cataracts a lot sooner, a lot

02:33:42.780 sooner. Yeah. Yeah. So that last thing I want to talk about was, are we ever going to have a day

02:33:48.580 when just as we look at hemoglobin A1C today, which is a pretty crude, unimpressive way to assess

02:33:57.120 glycosylation. I've ranted on this elsewhere, so I don't want to waste your time with my rant on why

02:34:02.260 I think hemoglobin A1C is not especially helpful outside of extremes, but I don't know why. I just

02:34:08.220 think the eye is the most sensitive end organ to excessive glycosylated hemoglobin. And it's also

02:34:15.860 one of the few things you can look directly at. So I know when I was in your office, just for

02:34:21.040 giggles, I wanted to have you do like basically an angio of my eyes, non-invasively. Non-invasively. 0.95

02:34:26.420 And I thought that was really cool. I liked knowing that I had beautiful little vasculature back there.

02:34:31.960 Your capillary network was the envy of everyone in the office. Really, really good.

02:34:36.940 Like what stands in, I mean, is there going to be a day when everybody's doing this every year? And when

02:34:41.780 we see changes there, we say, you know what? I don't care what your hemoglobin A1C might only be

02:34:46.700 5.5. You're quote unquote normal, but that might actually reflect higher turnover of RBCs. And in

02:34:53.320 reality, there's a problem. One of the really interesting things about the eyeball is that

02:34:57.780 it's a transparent organ, as you point out. So you can just sort of look in and see what the

02:35:01.740 problem is. It's not like, okay, there's belly pain. We need to do some testing.

02:35:06.960 Yeah. It's not like the spleen where you have to use more complicated tricks to look at it.

02:35:11.780 You can just look in. And because, for example, we have a layer of brain tissue readily available

02:35:18.340 for us to observe, including its capillary network. So we can look and see, are these

02:35:25.040 capillaries damaged, which is something you see in diabetics? Are they exudating fluid? Are they

02:35:31.180 leaking fluid? And that's a very early sign of diabetic retinopathy? Could you, for example,

02:35:38.560 image the lens and determine is glucose leaching into this lens? Does it contain more glucose than

02:35:46.200 you would expect a normal individual to have in their lens? Might that be a screening technique for

02:35:52.060 diabetic disease? But I think probably yes. And what about the fact that diabetes manifests primarily

02:36:02.260 as a microvascular disease in so many end organs, and we can actually directly visualize this

02:36:08.220 microvascular disease occurring? So if it's in the eye, it's probably in the kidney. It's probably in

02:36:13.560 the toes. And those are things that we can directly observe. And again, it's not binary, right? So it's

02:36:21.000 not, you know, we make the diagnosis in a very binary fashion. When the hemoglobin A1c hits 6.5%,

02:36:26.560 a person has type 2 diabetes. But, you know, at 6%, we just say they're pre-diabetic. And at 5.6%,

02:36:32.360 we say they're normal. But of course, if you understand everything we're talking about here,

02:36:36.780 that couldn't be further from the truth. It's not like a person's going to be perfectly pristine,

02:36:41.300 and then they're going to be diabetic. This is a spectrum. And I just think that this,

02:36:47.000 to me, is a much more interesting way to go about gaining kind of a foothold in our understanding

02:36:53.680 of a person's metabolic health is to sort of create this as now a new standard, right?

02:36:59.020 There's something I'm going to create as a standard for myself, right? Which is,

02:37:02.200 I want to make sure that these nearly invisible arteries and capillaries are perfect. And when they

02:37:10.220 cease to be, it's going to prompt investigation, right? Whether it be lipids, whether it be glucose,

02:37:14.560 whether it be any other thing that we can, you know, blood pressure, right? I mean,

02:37:18.400 all of the things that can damage a microvascular system, this becomes a beautiful window in which

02:37:24.640 we can look at them. What is the cost of doing that test? Yeah, it's super inexpensive to do,

02:37:30.720 but I honestly believe that we would see perturbations in the glucose migration into the lens

02:37:38.260 way sooner than we would see architectural changes in the retinal microvasculature.

02:37:45.680 And you measure that via pressure or shape as well?

02:37:49.820 So the technology to measure glucose in the lens doesn't exist commercially,

02:37:54.520 although it's being studied. You could look at how the lens essentially reacts to light that you

02:38:01.360 shine into the lens with a particular wavelength and determine how much glucose there is in that lens.

02:38:06.880 And is that abnormal compared to a normal population? But looking at the retinal vasculature,

02:38:13.480 we can do that with optical coherence tomography, and we can image in a non-invasive way the capillary

02:38:21.520 network. But again, I think that's going to happen. The changes there would happen after.

02:38:26.020 But I bet you see a lot of damage there in people who are unaware of their metabolic state,

02:38:30.500 right? You do, for sure.

02:38:31.960 But it's not the canary in the coal mine. You're saying the canary in the coal mine is actually going

02:38:35.140 to be the lens distortion due to the osmotic effect of glucose.

02:38:38.740 In initial diagnosis and screening, yes. But what happens very commonly is that a diabetic will

02:38:44.700 come into us and say, my sugar is well-controlled. My doctor told me I'm under great control. And we

02:38:52.860 look at their retina, and there's no way they're under great control. They have fluid exudating into

02:38:58.800 their retina. There are what we refer to as hard exudates. There are microaneurysms in their capillary

02:39:05.720 vasculature. These are signs that their diabetes is out of control. And then we'll say, I'm glad that

02:39:11.900 your A1C was normal. Would you mind going back to your doctor and mentioning that we see direct

02:39:17.700 evidence of problems with your microvasculature? And it's probably all over.

02:39:23.260 And how did the endocrinologist receive that news?

02:39:26.240 Typically, they will accept it. They'll say, okay, well, for this individual,

02:39:30.260 that level of A1C is not acceptable. They've been typically very receptive because they know we

02:39:36.860 can directly visualize. I mean, look, this is sort of my soapbox, but I really think that

02:39:41.660 ophthalmology should be more integrated into medicine than less because you guys do in some

02:39:47.380 ways operate sort of outside of what the surgeons and the internists and endocrinologists do.

02:39:52.220 Obviously, here's an example of where you're kind of saying, look, I'm seeing something and it's

02:39:56.660 important to your systemic health. I think there should be more of an integration of this. I think,

02:40:01.100 again, you said it earlier, and I think people might not have appreciated what you just said.

02:40:05.340 You get to directly look at the brain. You get to directly look at the central nervous system

02:40:09.880 in a way that a gastroenterologist can directly look at the colon, right? That's why colon cancer

02:40:16.280 screening is so freaking effective. You get to look with the naked eye directly at a polyp as it

02:40:24.540 becomes cancerous. That's one of the reasons I didn't become a gastroenterologist.

02:40:30.040 And we are thankful for them because of all they can save us from.

02:40:34.340 Absolutely. No doubt. But it is amazing that we have the ability to directly observe

02:40:39.800 brain and the vascular tree. And so that's very, very helpful.

02:40:44.940 Steven, this has been super interesting to me. I was a little intimidated coming into this one

02:40:48.980 because I didn't have the amount of time I normally have to prepare for this and try to

02:40:52.360 get up to speed on the topic. So I came in blind and ignorant, but you did a masterful job of 0.75

02:40:58.800 accommodating my ignorance. And I learned a hell of a lot and I'm sure everybody else did. 0.92

02:41:02.940 Well, thanks for having me, Peter. I really appreciate it.

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The Peter Attia Drive - March 07, 2022

#198 - Eye health—everything you need to know ｜ Steven Dell, M.D.

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