How the eye works (camera analogy)

40:38detector in the back, just like a camera. A camera has a lens and then a CCD in the back that the image falls on. And then the CCD captures how many photons are coming here versus there. What are the colors of those things? The eye is very very similar. Okay, the retina is an image sensor in the back. And this retina has photo receptors which are your rods and codes. You can think of that as your CCD. That's the thing that actually interacts with the light. And then if a little photon interacts with it, it's going to set off a little electrical signal. Then it goes through a bunch of different cells. They're called bipolar cells. Some of them are called amicron cells.

41:20And at the end of the day, you've got ganglen cells, which are the cells at the very end that take in all of that light information, convert it into electrical pulses, action potentials, and that goes through the oct optic nerve through your eye to your brain to the occipital lobe, and that's what's transmitting visual information to the brain's visual cortex. Okay? But it's really it's like mechanistically the eye is remarkably like a camera. You've got a lens and that lens you can squish. There's muscles on the on the end of your lens that you can squish and so on and so forth to let in more light, less light. That's your aperture, right?

42:02>> Um in in a normal DSLR, you've got the magnifying, right? And the magnification is like how much um like the the distance between your lens and the focal plane. >> Yes. Yes. >> But for us, we can I can focus on the microphone right in front of me and I can also focus on a mountain that's way way way far away, right? >> And the way that our eye can do that, we don't have the luxury of actually extending our lens. So what we do is we actually change the curvature of the lens >> in order to do >> in order to actually get different focal focal lengths, right? So it's remarkably

42:43like a camera. Okay? And in the back of your camera, in the back of >> the eye, you have the retina, which is this mini computer that takes in all of that information and then relays that back to the brain. >> It's sort of like the processing center. Once this comes once the raw data comes in, it kind of packages it up to send it upstairs. >> To send it upstairs. Exactly. And in the center of your retina, you have something called the macula and the phobia. Okay. Notice like I want you to just do this experiment where you're like looking at stuff. >> Mhm. >> Notice that you have a lot of detail in the center of your vision. >> Yeah. >> Compared to the periphery, >> right? >> Like if you really wanted to read

43:23something like that stuff that's on over over there, you would focus on it so that it's at the center of your vision. If you focus somewhere else, you wouldn't be able to read it. >> And the reason for that is you've got this structure called immacula and the phobia that has a high density of rods and cones, specifically cones actually that that that are the color receptors. So you you've got you've got like higher resolution there because the pixel density is higher. >> Not everything is not totally in focus all of the time. >> Yes. Exactly. And macular degeneration is actually a progressive disease that

44:05damages that macula. So >> the the macula is in the in the middle, right? And you can have two types of AMD, macular age related macular degeneration. There's the wet AMD where basically the abnormal blood vessel growth. There's a bunch of blood vessels in your eyes, right, that are keeping these cells alive, giving it oxygen, things like that. Those blood vessels can leak, rapid vision loss. And then there's dry atrophic AMD. Okay? And that's the gradual thinning of the macula. You get these extracellular deposits where the the cells are sort of just dumping their trash and then that kills everything. And all of that accumulation happens and it kills all of

44:46those cones and that are that are there in that center in that center. And so that center of your the center of your visual field >> Yes. >> is the thing that goes away >> which is like obviously