The Science of Human Vision | How We See The World Around Us

TRANSCRIPT

Why is it difficult to sneak up on an octopus? That might sound like a dad joke, but it's actually a semi-serious question

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with a scientific answer that goes to the difference between octopus eyeball design and human eyeball design.

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If you think you know the answer, then leave an answer in the comments. But if you're curious to know more then you're in luck, because today I'm

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speaking once again with Paul Graham. Paul is a leading Gold Coast optometrist

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with over 30 years of experience, who's also the owner of Harmony Vision Care.

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In this interview, we're going to be talking about

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But first, who am I? My name is Paul Sallaway. I'm the owner of Optics Digital Marketing. We're an agency that helps independent

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optometrists to grow their practice. So hello, Paul. Good to see you again. Yeah, likewise.

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So in your training as an optometrist, did you ever get the chance

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to dissect any octopus eyeballs? Not octopus eyeballs. I think we dissected ox or cow eyeballs, possibly.

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Pig's eyeballs, possibly. Well, I've dissected a few octopuses, but mostly on the dinner table.

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As you know, I've spent a bit of time in Japan, and it's a common dish amongst Japanese cuisine.

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But yeah, so this is something I learned recently, is that like, octopus's eyeballs have evolved like down a different evolutionary tree

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than humans and most vertebrates. But in some ways, you can maybe argue that their design

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of an eyeball is better because an octopus doesn't have a blind spot, whereas humans do.

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You can test this for yourself. There's something I discovered where you can draw a cross and a

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circle on a bit of paper. As you hold it away and cover one eye, you can see the cross out

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of your peripheral vision as you bring it closer, it disappears. Then as you bring it closer, again, it pops back into view, which is a fun thing to play with but apparently,

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Anyway, octopuses, our eight-legged friends, don't have a blind spot. Yes, I thought that was interesting, Paul.

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Yeah, look, and when to how the human visual system is organized and you compare

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it to other animals, then there will be some similarities.

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And it's really interesting when you see that convergence and you look at how the similarities between octopi and humans, our manipulation of the environment.

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Both of us have got this high ability to manipulate the environment. And so it'd be interesting to dig in and see if part of their

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ocular and visual development is because of that ability. And certainly the way where our eyes are positioned on our head is also thought

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to be an outcome of the environmental niche that we live in. So a lot of the way we process the world is unique to our specific niche

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of the planet- That's right. If you're swinging through trees and jumping from branch to branch,

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I guess it helps to have the eyes in the front of your head, doesn't it? Yeah and they do believe it's not just the swinging, it's the cluttered environment.

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When you've got things in the way that get in the way, you still need to be able to see.

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And that's why Mark Changizi has a fascinating book on this, and it's quite an easy read. You don't have to be an optometrist to read it.

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And so his stuff is about why we have two forward-facing eyes. And we have this see-through vision.

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If you put your hand up, your hand goes see-through and your brain fills in the rest. And the idea being that primates were living in cluttered

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environments and still needed to be able to see. An outcome of having two forward facing eyes, though, is that, yes, we've got

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that good 3D vision for grabbing things. Whereas if you're a horse or a cow or something, it helps to have eyes

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at the side of your head so you can see if any lions or other predators are coming. Yeah, and some animals, and I think you were saying it's

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hard to sneak up on an octopus. It's hard to sneak up on a rabbit for the same reason because they've got their eyes on the side of their head.

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They can almost see their own tail. Well, we won't dwell too much longer on seafood, but in this interview,

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I'd like to talk with you more about the science of vision, because I think it is a fascinating topic.

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Why don't we start with the front of the eye and work our way backwards as it is.

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Tell us about the front, the cornea, isn't it? That's a common way of looking at it, but I just probably want to premise it

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because it will circle back around is that I like to think of vision actually happening from here forward because we're actually reaching out, projecting

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and trying to predict what we're doing. And rather than it just being this light goes in, then we process it.

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We're actually actively looking for which bits of the light are important to us. And if we look at the eyeball as a optical system,

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the first surface the light has to pass through is the cornea. We can see that the cornea is quite curved.

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And so, it does the majority of the bending of the light to help it

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focus at the back of the eye. And then we have a lens which has less hour.

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Its main role is to adjust and we'll get to that one.

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And probably one of the most important parts of the cornea is actually the tear film that sits on the front surface.

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The way I have heard it described, and I find it a useful description, is if

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we think of the cornea as actually a bit like frosted glass, glass that's been etched to be frosted, you pour water over a frosted glass, it becomes clearer to look through.

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And the corneal surface is very similar. So, we need this tear film to create this nice, clear, uniform surface.

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And if we don't have a clear, uniform surface, then we get blurred vision. And so some people might come in thinking that they have a refractive problem or

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a focusing problem, when in fact, they have a problem with their tear film drying out in some way.

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Now, one of the most common issues with the tear film drying out is often just because we live a modern life and we're not blinking enough.

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And we need that lid wiper action to wipe the tears across the front surface.

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Or we're doing it where we're not actually blinking fully. And so we get part way and we leave this area to dry out, and get exposed.

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And we often get remarkable improvements over several weeks of just getting people

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to become more aware about how they're blinking. And one of the easy bits of advice is a dozen times a day, take the moment

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to do 10 to 12 good blinks. And a good blink is not squeezing your eyes shut. A good blink is just making sure they close.

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And then that way we get that lovely scissor action of the eyelid sweeping stuff out of the way and also spreads those good oils across the tear film

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to keep everything nice and clear for us. Yeah, it seems to be like something that I've noticed more people talking

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about in recent years, the whole dry eye disease or dry eye syndrome. And I think it's really come to prominence since the pandemic, to some extent.

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Maybe it's because we're all spending more time looking at computer screens during

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those lockdown years, but it seems like more people are aware now of dry eye and how that affects their vision.

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Yeah, and we're certainly seeing it in younger people than we did. It used to be something that was an age-related issue,

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but we're seeing dry eye at all ages and including in kids.

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And so you'd have to look at the modern life and exposure to digital devices and

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things like that being part of the issue. All right. So that front of the eye, that's the cornea.

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That's the first window that the light passes through, if you like.

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Now, what is astigmatism? Because this is a word I think that gets thrown around a lot, but I'm not sure if

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everyone actually understands what it is. So tell us about astigmatism. Yeah, look, it's an interesting one, too, because

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there's a lot of layman terms for vision problems out there. And astigmatism is one that's not a layman term.

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It's actually the proper term. But I think it still gets kinda confused. The vast majority of astigmatism is actually from the cornea.

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And we generally like to think of the cornea is typically fairly spherical. So the same curvature all the way through.

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And the reality is it's slightly barrel-shaped. And so if we think of a barrel, it's quite curved this way,

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but it's flatter that way. Another example might be a dessert spoon shape rather than a soup spoon shape.

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And once you go outside a normal range of differences in curvature across

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compared to up and down or even obliquely across this way, then you start to get

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the spreading of the optical image. And so if you've got a high amount of astigmatism, then you can't get a sharp

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single plain image at the back of the eye, and the image tends to get spread.

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And so some people might interpret that as blur. When you're younger, though, you can quickly focus between the

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across through the image spread and move that image around and slowly process it over time. So some people find that they can see, but it seems to take

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a while to come into focus. And other people might get starriness of lights. You get these lines appearing through lights at night.

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And that could be caused by aberrations. But a more common type of aberration is actually astigmatism.

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And so that's something that... Sorry, that's something that glasses and contact lenses can correct for, is that right? Absolutely.

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So, if astigmatism is bothering someone, then yes, we can use glasses, we can use contact lenses as another way of correcting it.

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Where astigmatism comes from is an interesting one. There are certainly inheritable profiles that you see.

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There was a very interesting group of studies done several years ago where they looked at orchestral, professional, orchestral musicians.

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If you perform in an orchestra and you're, as an example, first cello,

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you practice and perform in the exact same location with your stand in the same place

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and your head position and the conductor always in the same place. And because you're practicing for hours and hours and hours in those position,

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you might find that your head is turned a particular way and your eyes are pointing a different way. And they could almost predict from your common head position and your gaze

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which eye was going to have more astigmatism than the other. And so there is some indication that the way we use our eyes might

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be responsible for some astigmatism development. Part of the challenge is once it's there, it's very hard to undo.

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So it brings around posture being an important part of moving symmetrically,

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sitting symmetrically, just to try and... If that is an influence on astigmatism development, it's all the more reason to

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take breaks and make sure you're sitting up straight and sitting well and looking after yourself. Yes.

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And then you've got irregular types of astigmatism, which we've talked about before, things like keratoconus and pellucid marginal degeneration

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and you're getting into more diseases that create irregularity where it

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becomes a lot more difficult to correct the astigmatism of glasses, and you have to start getting down into special types of contact

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lenses to correct those things. Sure. Okay. That's interesting.

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So when you get someone in your consultation room, do you ask them which section of the orchestra they're in, the brass, woodwind or string section?

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Well, look. We've got the benefit, our practice has been around for a few decades now.

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And if you've got a patient who we've been seeing for quite some time and they start developing some asymmetries, astigmatism one eye more than the other,

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I do ask questions of, have you changed your set up of your workstation? Have you now got a screen off to the side?

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Are you sitting side on a bit more? So I do ask about those things in some situations.

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Absolutely. I didn't realise that astigmatism is something that you could actually develop.

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I just thought it was something that you were born with. Yeah, no, it can definitely develop.

What Are Cataracts?

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All right. So that's the cornea. Now in your model there, you showed us the lens, and that's like

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the second window, if you like, that it passes. Can you tell us more about how that works? All right, so.

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The basic format is that you've got the ciliary muscle here,

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and you've got this elastic bag that's suspended on little strings called zonules. And then you've got cells inside that are lined up in really regular lines,

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and it's that regularity that keeps it clear. Now, the idea of the lens is that the ciliary muscle will contract and

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you get this change in shape in the lens. And so they call that accommodation. And so the idea being is that we have, like I was saying,

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the cornea is the main getting the image close to the retina, and then the lens helps us adjust depending on what

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distance we're looking at. That lens changes shape in order to adjust the focus at near.

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And that's the one thing that we, like other parts of our body, we lose flexibility as we age and we lose flexibility in that lens.

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And so adjusting our focus from distance to near becomes more difficult as we start

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to celebrate anniversaries of our 39th birthdays.

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So if you're using a digital device a lot and you're looking from a close screen

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to something that's on the other side of the room, and you're doing that a lot. Do those muscles, I think you call them the ciliary muscles, do they get tired?

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Is that what leads to eye strain? Is that the cause of what they call digital eye strain?

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Yeah. And so the accommodation system, I mean, the whole visual system is designed

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to search the environment for things that matter to us for survival purposes.

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And our visual system was developed for moving through the world and not

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sitting still looking at two dimensional screens. One of the ideas that I think fits most is that the ciliary muscles are not really

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designed to hold posture and hold focus for long periods of time. And so you get this fatigue that sets in.

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And you can get some obvious changes when we look at patients where

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the focusing is fatigued and someone's under-focusing. Or they might be pushing their focusing really hard, and you see that they're

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over-focusing, and it's all a reaction to the brain detecting that something's going out of focus.

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But what you also see, and the research is starting to show this a bit more, is we get these changes in the fluctuations

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in the ciliary muscle, and that's one that's probably linked to most to asthenopia, which is visual discomfort, digital eye strain.

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I like to say to patients, eye strain is not a new thing.

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It's just a new thing to more people. If you're an academic, you are often reading books

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and potentially getting eye strain and potentially myopia. Whereas, and if you weren't academic, you're outside playing.

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Whereas it doesn't matter what your level of ability is now, you're on a screen. And so that has made eye strain a much more common thing.

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Okay. And so the lens. So I've heard that

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Cataract and cataract surgery is now one of the most common

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types of surgeries that are performed in Australia now. So tell us about what cataracts are.

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And probably a good segue is that what happens before you develop a cataract is

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you develop presbyopia, which is that basically the lens grows, keeps growing bigger throughout our life.

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And so that ciliary muscle runs out of room, but it also starts to get harder in the centre.

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Those cells compact and get harder and make the lens less flexible.

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So that's presbyopia. So that's when we need to start having reading glasses in our 40s and maybe 50s.

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If you know some people, it takes a little longer to get to that point. And that's also why we have that frustration of the glasses seem

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to keep getting stronger and stronger. And people like to blame the glasses, but really, it's just an aging process.

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It's a bit like chasing our grey hairs and our wrinkles. The presbyopic process keeps going. Now, that eventually then, I think, is the same process that leads

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to cataracts in most cases, where those lenses, those cells get so dense that they start to discolor.

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And so you get that rather than being lined up and regular, they start to go wrinkly. And so you get these spots and opacities and you get this darkening.

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I mean, one comment or cliché was that every decade of life is like wearing

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another pair of sunglasses as far as the lens is concerned because it goes more yellow. So it's absorbing UV, it's aging.

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And so that's what becomes a cataract. Eventually, when you're at risk of falling or not passing your driver's

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license anymore because you've got something that we can no longer correct with a pair of glasses.

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And so in the later decades of our life, we have access to cataract surgery,

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which is, yes, it's a very, very common surgery because it's aging population affects so many people, and the techniques have really become

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quite advanced now that you can almost elect to have it done early as a refractive procedure instead of laser surgery.

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But more commonly, it's done once you've actually hit the point where you can't see anymore.

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In Western countries, it tends to be, I say we tend to get it done when it's a bit of a nuisance factor.

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My wife and I have had the privilege of working in Vietnam to assist ophthalmologists

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doing cataract surgery on poor people, and they're developing them much younger. And to a point where it's not a nuisance factor,

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They're actually, it affects their livelihood. It takes out a family member who has to look after them. That person is not able to contribute to the family.

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And so what is considered to be a relatively simple nuisance here can be

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absolutely life-changing in other countries.

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Okay, so that front of the eye, the cornea and the lens is,

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just to get some terminology out there. Is that what optometrists mean when they're talking about the anterior of the eye? Correct.

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Anterior eye is a cornea, iris, anterior chamber, and the lens,

What Is Macular Degeneration and Glaucoma?

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ciliary body in the lens. Okay. So let's go to the back of the eye now, the posterior of the eye, if you like.

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So there's a lot happening at the back of the eye as well. And there are eye conditions that come with that.

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So let's talk about macular degeneration, because I have heard that age-related macular degeneration is one of the leading

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causes of vision loss in the country. So it gets to a point where the retina and the light receptors are

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very highly metabolic. They're churning over all the time. As part of dealing with light, they have to recover.

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And that's why we get that bleaching. If you get a flash of light, that's all the light receptors being

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bleached out, and then they need to recover. And it's part of all our tissue not recovering as quickly.

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One of the risks is that your retinal tissue at the macula doesn't recover as quickly as well.

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And if you're not getting good recovery of the cells at the back of the eye, then that impacts on your ability to see clearly.

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And you start to get other issues with not enough oxygen.

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And you get not enough oxygen, then you start to get new vessels growing and new vessels leak, and they create problems.

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And so, yes, it can be quite a debilitating thing. One of the biggest reversible risk factors they talk about with macular

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degeneration is smoking. And so being a nonsmoker is really important,

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and you can actually sort of the earlier you quit, the better.

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There does seem to be some history involved as well. And again, with the advancements of technology is

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that they've got the ability to try and slow it down, but the loss of sight now through techniques with ophthalmology, which is very different to when I was

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going through university, there was nothing you could do about macular degeneration. It was all about trying to use magnification and various

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optical devices to try and get some quality of life back. Whereas now, if you talk to ophthalmologist,

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probably their two biggest things that they're busy with is cataracts and injections for macular degeneration, and you call retina type work.

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And the way macular degeneration manifests itself,

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the symptom is that you lose that central part of your vision, isn't it? Or it becomes greyed over and or distorted.

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Distorted. Yeah. So sometimes some people will see it as a patch in their vision,

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and they report having to look off to the side to see things, or they may get some misshapen

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parts of their vision, typically in the center. There's something called, I think it's called an Amsler test, isn't it?

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Where you can look at a grid of lines. If the grid doesn't look perfect, if it looks a bit distorted, that's a

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way you can self diagnose to an extent that you might have early signs of macular degeneration.

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Yeah, and look, if someone has early signs, or they're concerned about it, then yes, you look at an Amsler grid.

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The trick is you look at a little spot with your correction on. So usually if you need reading glasses and you're holding it at the reading

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distance, there's lots of little lines. You're looking at central dot, trying to use your peripheral vision just to pay attention to any loss of lines or any distortions in those lines.

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Okay, so that's macular degeneration, whereas I think another eye condition,

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which is just relatively common is glaucoma, isn't it? So that's where you lose maybe more of the peripheral vision.

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So what is glaucoma and what causes that? Yeah, look, it's considered to be...

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You might consider it to be a posterior eye condition because that's where we see the changes. But it's probably a hole of eye issue because we're dealing

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with the pressure of the eyeball itself. And if we think of the back of the eye as the bowl,

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we have the nerve fibers running across the surface of this bowl, and then they collate together,

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they become the optic nerve and leaving the eye. And so the pressure is controlled around

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the ciliary body, and the anterior chamber.

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And if the pressure goes up, then it puts pressure on those nerves and causes nerve damage.

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And if you get nerve damage, then you start to lose your peripheral vision first. And they often call glaucoma the sneak thief.

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So even though we talk about pressure, we don't necessarily feel the pressure because it's a slow creep over time.

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And if you become conscious of... Because we don't detect blur in our peripheral vision, if you start to become

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conscious that you're not noticing things, and people start to surprise you at the shops and things like that, you just feel like you're missing more,

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then a good lot of the damage is done. So that's why there's a strong recommendation from optometry

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organizations that once you get into your 40s, because that's when the risk factor for developing glaucoma starts to increase.

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Getting your eyes tested every couple of years, a routine vision exam includes

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looking at your eye pressure, looking at your optic nerve. And then with things like you can see

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the Revo machine here, that's my OCT. We use that to actually measure the thickness of the nerve fibre,

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compare you to what we expect for your age and demographic. And then if we are suspicious that something's changed,

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then we can compare any changes in the fiber thickness over time. Coupled with doing visual field tests and pressure measurements

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and things like that. And we've talked quite a lot on other interviews about myopia and how that

24:55

is something that develops in your early years where the eyeball becomes more elongated.

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That phenomenon, I think you call it axial elongation. So how does that lead to a higher risk of

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these kinds of posterior eyeball issues later in life? You're effectively fine that the retina does not keep up with the eye growth,

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and so you're effectively stretching that retinal tissue and making it thinner and you're weakening it. So it makes the tissue more prone to tears in very, very high degrees of macular myopia

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you have a high risk of myopia macular disease and glaucoma as well,

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because you're changing the natural structure of the eyeball. And so these processes don't work as well as they did.

How Do Biomechanics Affect Your Vision?

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But it's all down to stretching. All right. Well, we've often talked about how vision comes from not just the eye,

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not just sight, but our whole body is actually

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like an interconnected visual system. And that includes the head, the neck, and so on.

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So tell us a little bit about what you're seeing in your practice there

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in terms of those biomechanical issues that can have

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an impact on people's visual ability. And I think we've talked about it before that the brain is just trying

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to predict what's out there. And we're searching for good information. And as part of that process, of if light is moving across

26:31

the back of the eye, your brain needs to make sense of where that movement of that image comes from. Did it come from an eye movement?

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Did it come from something moving in the environment? Did it come from a body movement? And we were discussing off camera earlier that there's this great video of a bird

26:46

of prey where it's able to hold its head still while its body moves around it. And it just shows how much the brain needs to coordinate what's going on with the rest

26:54

of the body, even just to hold a visual image to be stable in that situation. And as much as we don't have that level of finesse or control like

27:02

a bird of prey, it still fits for most animals that we need to integrate all those movement sensors.

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Now, the humans have large, heavy heads on our shoulders. And so whiplash injuries, concussions, brain injuries have a great impact on some

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of these proprioreceptive information centers, where we get information about head

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and eye movements in our midbrains right here as well. And so those other senses being damaged, or at least the interruption between

27:34

the connection between vision and those centers can really make people feel disorientated. So you get things like vertigo and dizziness that can be created

27:41

by specific damage to various things, but also just the ability of those things to talk to each other.

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I've even had a personal experience of having some neck tightness that resulted in double vision. There's nothing wrong with my binocular vision, but it just goes to show that if

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you're not getting the right messages from the rest of your body, your visual system doesn't know what to do with it. So it just shows the interconnectedness of it all.

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And we're working closely with physiotherapists and other professionals because of that loss of connection and talking between

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the various systems where we're trying to get those things reconnected or rebuilt, rehabilitated.

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Yeah, that video of the bird of prey, that's on your Facebook page.

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That's where I saw it as well And it is amazing how that bird's head is just perfectly still, even though its body is being buffeted in the air currents.

28:40

And I think I might mention, when I was younger, I used to play cricket a bit I had a very brief and mixed career

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at the Helena's Valley Cricket Club, which we don't need to go into. But one of the things that the coaches always said is, if

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you're batting in particular, you got a ball coming towards you at 140, 150, kilometers an hour.

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And the secret is to keep your head perfectly still and just track the ball with your eyes.

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It seems like all the best players are very good at doing that. Yeah, and look, I'm an archer, and so I think there's a level, too,

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where you've got to learn not to overthink it. And we often talk about, is it better to have one eye open or

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just only one eye open or both eyes open? And I'm in the group that says both eyes open because you need to be judging space

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and you need to be allowing the peripheral vision, your more reactive part of your visual system to be there.

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I think a big part of sport is that lots of practice means that you're letting

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the brain react to various experiences. And I think that's the critical headspace very good athletes get into,

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is that they stop thinking about what they're doing and just let the

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fast thinking part take over, get out of the way. I think that's the biggest issue with...

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I was talking about this the other day that sometimes some of the best coaches are the ones who aren't necessarily athletes to begin with because

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they overthink, they can analyze and look at stuff, but you can't be over

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analytical if you're the athlete. You've got to stop thinking sometimes. But yeah, very important to have yourself set up so that you can take

30:25

advantage of as much as possible. And I know in cricket, it's head straight, head-eyes level.

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You want to be front on so that you're taking best advantage of having that full visual field and the two eyes working together as good as possible.

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I remember reading a book written by Don Bradman.

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Anyone in Australia doesn't need the explanation of that name. He's the greatest batsman that's ever lived.

30:54

That's just an objective fact. I remember reading that in his day, people were wondering what

31:02

made him such a great athlete. A lot of people were speculating, well, he must have better eyesight

31:07

than the average human. He actually, I think, went to a university in New South Wales,

31:13

and they did some tests on his eyes. To their surprise, they found out that his eyesight was actually no better than,

31:20

actually, in some cases, a little worse than some of his peers. But where he appears to have had it, where his skill appears to have come from

31:29

is this prediction machine that you mentioned. His reactions, his reflexes were just so much better than anyone else.

31:40

So his visual predictions, if you like, about where the ball's going, what he's going to do about it.

31:49

It seemed to be so much better. Actually, just coincidentally, I read an article by Ian Chappell recently

31:54

where he talks about one case where where Bradman, for a particular reason, he

32:02

particularly wanted to do well in this innings. And so in some ways, he was getting in front of himself.

32:09

Like you said, you've got to remove yourself and let your brain do the work. But because he was getting in the way of his normal behaviour,

32:18

people watching his innings said that he looked like a normal batsman all of a sudden. So it's amazing how our brain just operates on autopilot sometimes.

32:30

And you look at a good example is Tiger Woods, just one of the greatest golfers out there, and then he had some very

32:39

dramatic personal issues. And he went from being the best to way back in the field, and it showed

32:46

how much mindset was a big part of it. There's a really interesting phenomenon called quiet eye,

32:52

which is an observed moment that athletes, professionals, demonstrate where they

33:00

pause their fixation on a particular area. And probably the easiest one to use as an example is the basketballers

33:08

usually have this quiet moment of normally about half a second, I think, from memory,

33:14

longer of looking at the edge of the hoop when they shoot compared to someone who might be serious, not quite at that same level.

33:26

But you can't recreate it. You can't force people to spend half a second to

33:33

a second longer looking at the edge of the hoop and expect to recreate it.

33:39

It's an outcome of the way that those athletes train and use their vision

33:44

as opposed to something that's trainable. That's interesting.

How Do Strokes Affect Vision?

33:49

Well, let's talk a little more about... Let's finish up by talking about the brain, and how that processes

33:56

visual input. So we've talked before about concussion.

34:03

So concussion and stroke. I mean, stroke is a common problem, particularly for older people.

34:09

How does stroke impact on our visual systems? Stroke, in particular, one of the outcomes, depending on

34:18

how it affects the pathways so you can often tell where a stroke may be if there's been some visual field loss.

34:26

So you get a darkening of where you just can't see anymore in part of your visual field.

34:31

And different areas of the visual pathway from the back of the eye through to the back of the brain are susceptible, different parts of your

34:39

visual field being affected by that. And so because there's a bleed, it actually damages the nerves,

34:46

and you get ischemia so you get nerve loss. So that's one of the things that can happen is you actually just lose part of

34:54

your ability to see in your visual field. And so we use a thing called a visual field test to detect those things.

34:59

You can get, depending on the areas of the brain, you might have issues

35:05

with connecting with recognizing things. So your vision may be okay, but you can't find the label of things.

35:11

I remember a lady who was in her 80s, and she had a stroke, and she says,

35:17

I can see the letters, but I can't tell you the names. So I said, well, how about you draw them in the air for me?

35:24

And then so she started drawing the shapes of the letters in the air, and then she was able to say them.

35:29

So she was able to, she lost the ability to directly see and say, but she could say them if

35:36

she brought some motor system in. So you get these very interesting losses of function.

35:43

And I don't mean to, it's not a cold-hearted fascination.

35:48

It shows how much the brain is a fascinating thing, but that can be quite debilitating for people.

35:55

Part of our strategy is that we're looking at, if someone is light sensitive. Are we using tints to try and help them?

36:02

If someone's had double vision that's resulted from concussion, stroke, brain injury, how do we solve the double vision?

36:08

Are we able to get the two eyes working together again through vision training? Do we need to use some partial occlusion to try and block some

36:17

of the double vision? And so that's the things that we're starting to... That's what we're considering when we're seeing someone is,

36:23

okay, what's the nature of the injury to your visual system? But more importantly, what is it that we might be able to do to get

36:30

your quality of life improved, either through removing interference caused by the injury or trying to rehabilitate function again?

36:41

Can emotional stress also interfere with their vision because I

36:47

don't know if you ever saw that HBO series, Band of Brothers, which is based on actual events, actual people.

36:54

But there's a character in there, one of the soldiers who was in France after the D-day.

37:01

And because of the stresses of battle, he experienced hysterical blindness.

37:06

Like, he just out of the blue, his vision just stopped. And then a little bit later, just came back again for no reason.

37:13

So it seems like that's an extreme example. But I have heard that stress can also interfere with our visual abilities.

37:23

Yeah, look, there are some of them. There's a bit of conjecture about some of the syndromes out there.

37:28

There was one that was called see, some of the names. There was one called stress syndrome. There was another one called bilateral hysterical amblyopia,

37:36

where you get a loss of ability to see central vision clearly without any

37:43

signs of pathology or refractive error. So, no short-sidedness, no astigmatism, long-sidedness.

37:49

And the literature seems to indicate that it's linked with some period of stress.

37:57

There is a saying in other fields, and I don't know if this is still a medical thing, they call it conversion, where your brain wants

38:06

to shut something down. So this is purely anecdotal. You hear stories of a child who had an injury to an arm years ago and then has

38:15

a period of high stress, and then that becomes paralyzed because the brain goes, I'm stressed, I need to shut something down.

38:22

Okay, what area was weak? So let's shut that down. And there's some conjecture about whether that's part of what we

38:28

see visually as well. Yeah, I mean, this is why I'm a lot less concerned about

38:36

AI than many people, because I think that we don't really understand how our own brains work yet.

38:43

So it's a leap. It's a leap to think that we can create a machine that exactly mimics

38:49

what the human brain does. I have to say, though, it's that certainly the parts of

38:56

visual neuroscience owe a lot to the AI and robotics industry, because a lot of what we understand about the human visual system comes

39:05

from the computer industry, trying to work out how to make a bit like reinvent the octopus eye.

39:11

How do we make these things work? And so it comes from trying to solve problems. And effectively, that's the way the visual system has developed

39:20

everything that we do. And we even look at dysfunctions in this practice is, that some dysfunctions,

39:25

if they're a change in visual behaviour, so people develop eye teaming and focusing problems as a result of what they're doing

39:32

with their eyes, their habits. We sometimes ask the question, what problem are you trying to solve

39:38

by using your eyes that way? What stresses are you dealing with? And so it's thought that, that's the way our visual systems have evolved.

39:47

And like I'm saying, AI and computer, they're trying to solve problems. They're trying to get these robots and computer systems to do things

39:55

with visual information. And so we learn a lot through their convergent thinking about things.

40:03

Interesting. All right. Well, we might wrap up there, I think.

40:10

So is there anything else that you'd like to add, Paul? No, I think this has been great deep diving into the stuff that we

40:19

think in the background. That's what keeps me fascinated with vision and optometry is just thinking

40:24

about the brain side of things as well as, all the way through. Like I said, I like to think from back here forward.

40:32

So it's been great to be able to share some of that stuff that we read and nerd out on in the background.

40:39

And thank you for using the correct collective noun for octopuses, by the way.

40:44

Octupi, not octopuses. So tell us, how can people get in touch with you at Harmony Vision Care?

41:00

plus book appointments.

41:10

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41:25

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41:37

All right. So thanks a lot, Paul. And until next time, everyone. Have a great day. Thanks again, Paul. Thanks, everyone.