- What are the major forms of vision loss in childhood and in adulthood? And what can each and all of us do in order to find out if we have one of these conditions and therefore treat it effectively? - Yeah, that's great. You know, let's start by just reminding ourselves what are the major causes of vision loss?

And these are gonna differ where you are in the world, but the number one cause of low vision is actually refractive error. People who need glasses and especially in other countries, affordability, access, can't even get glasses, okay? So that's just refractive error, but that's fundamentally correctable. The next most common cause of vision loss is cataract.

Cataract is the blurring, the aging of the lens inside the eye, behind the cornea. We talked about how that is responsible for focusing light under the back of the eye. It also has to be clear enough that the light gets through the lens. And a cataract is a normal aging process.

You know, as I said, if we all live to 100 or 110 years old, we'll all get cataracts, we'll all need cataract surgery. We actually, as you know, in the eye clinic, we see cataracts years or even decades before they're affecting your vision in a meaningful way. So the cataracts are forming and that's okay, but at some point they get bad enough that it's time to take them out.

We've actually solved for cataract surgery pretty efficiently. We can do a four to eight minute surgery. Maybe if we're taking our time, it's 10 or 12 minutes of surgical time. Take out a cataract. It works beautifully 99 point something percent of the time. We put a plastic, a clear plastic lens inside the eye, exactly where your lens used to be.

And there's even lenses that can flex or focus light from far and near. So cataract is fundamentally a, there's still room for improvement, but it's fundamentally a solved problem. The problem is, is that worldwide, there aren't enough cataract surgeons. There's not access to care. The machinery or the lenses cost too much money in developing countries to get out to the number of people who would need them.

So it's actually just, again, an access to care. Cataract is a reversible, treatable, easily treatable problem, but it's number two on the list of causes of vision loss in the world because we don't have enough access to care. We need a lot more sort of programming around global ophthalmology, global eye care to solve for cataract, just to bring that solution to countries around the world.

Then after that, you start hitting the eye diseases that lead to what are currently irreversible, non-reversible causes of vision loss. The number one cause of irreversible vision loss in the world is glaucoma. So what is glaucoma? Glaucoma is actually probably a little cluster or constellation of diseases that we lump together.

It's a degenerative disease, like a neurodegeneration. We talk about neurodegenerations in the brain, like Alzheimer's and Parkinson's. Glaucoma is a neurodegenerative disease. It happens instead of affecting one or a different area in your brain, it happens to affect the optic nerve that connects the eye to the brain. And we need our optic nerves to carry all the visual information from the eye to the brain.

And so if your optic nerve is degenerating in glaucoma, and I should add, there are other optic neuropathies, so-called diseases of optic nerve degeneration. For example, you can get a stroke of the optic nerve. You can have an inflammatory disease like multiple sclerosis called optic neuritis that affects the optic nerve.

So you can get other optic nerve diseases, but glaucoma is by far the most common optic neuropathy. And the problem is just like spinal cord injury, which is also part of the central nervous system, the brain, the spinal cord, the retina, the optic nerve, that's the central nervous system, and there's no regeneration.

And that's why spinal cord injury leads to permanent paralysis, while optic nerve injury or optic nerve degeneration, unfortunately leads to permanent vision loss. So in the case of glaucoma, how do we get ahead of that? Glaucoma has two major risk factors. One is increasing age. There are actually infantile and pediatric glaucomas, unfortunately.

And those can be much more aggressive, much more damaging when they present so early in kids, in babies and in children. Most of the kind of run-of-the-mill glaucoma usually presents in adulthood and even in the aging adults. So much more common after 50 or 60 or 70 years old, increasing.

The other main risk factor for glaucoma is increasing eye pressure. The eye actually, you know, it stays inflated. It's a balloon, it has to stay inflated. We need some amount of eye pressure to keep our eye as an inflated balloon. But if the eye pressure goes too high, and we talked about this before, you won't even feel it if it slowly gets too high.

If the eye pressure goes too high, that causes glaucoma. And that's one of the things that we talked about, you really include in a comprehensive eye exam when you're just getting a screening checkup at your eye care provider, at your optometrist or ophthalmologist office. They're gonna check your pressure.

And just as a screening tool, check to make sure it's not too high. We can treat glaucoma today by trying to reduce the impact of that high pressure by lowering the eye pressure. So we have treatments for glaucoma that target the eye pressure. We have medications like eye drops.

We have lasers that can be used inside the eye that can also lower the eye pressure. And ultimately, if we need them, we also have surgeries that can also provide an outflow that lets the fluid out of the eye in a controlled way so that the eye pressure can be brought back down into normal ranges.

Again, the reason that glaucoma ends up being the number one cause of irreversible blindness in the world is number one, we can't get those therapies everywhere in the world. The affordability of eye drops, the access to lasers or surgical procedures around the world isn't equal to what it is here.

And even within our country, people may not be accessing healthcare effectively to get screened for glaucoma or to get treated for glaucoma. The other big problem with glaucoma is that it affects our peripheral vision first. And only very late in the disease does it pinch in and finally pinch off the center of our vision in typical glaucomas.

And that's a real problem because we don't notice if our peripheral vision is down. You know, our peripheral vision isn't that good to begin with. And if you're driving and you can see a pedestrian step off the sidewalk, you think your peripheral vision is fine, but actually your peripheral vision could already start being damaged by glaucoma and you won't notice it in regular daily life.

And that's where the importance of screening and early detection really comes in for glaucoma. What we don't have for glaucoma, we can come back to like kind of what's the cutting edge or the future in these eye diseases. What we don't have are treatments that really target the optic nerve degenerative process.

And we can come back and talk about that. So that's glaucoma and optic neuropathies. Then the next two major causes of currently largely irreversible vision loss are age-related macular degeneration and then diabetic retinopathy. Now age-related macular degeneration is just like it sounds. Major risk factor is age. It's very common and actually in the developed world, you know, countries that are more developed, also countries that have a larger Caucasian, white population, it's more common in certain populations than in others.

It actually is, you know, definitely a leading cause of vision loss in the elderly population, for example, in the United States. And there's two forms of macular degeneration, but they both end up targeting the same part, the same part of the retina. And the part of the retina is really like the rods and the cones that we talked about before.

The rods do your low light vision at nighttime, primarily your cones do color vision and bright light, you know, sort of normal lighting that we experience, you know, through most of our awake day. And in that back of the retina, you can have what's called dry macular degeneration, which is a slow, thankfully slow, but slow insidious disease that causes the degeneration of the rods and cones and also the support cells that help feed the rods and cones and take care of the rods and cones.

They're called RPE cells, retinal pigment epithelium. It's not really critical, of course, the names of every different cell type, but these are like the light collecting cells in our eyes in the retina, and they degenerate in macular degeneration. And in the dry form, there's the slow degeneration, but some percent of people with the dry form of macular degeneration will actually convert to what's called the wet form.

It's called wet because new blood vessels actually grow inappropriately under and even into the retina, and new blood vessels, unlike our mature blood vessels, tend to be leaky. And so the fluid leaks out of those blood vessels, gets into the retina, interferes with vision, and that can lead to a much more acute loss of vision.

Now, we have some treatments for wet macular degeneration. We have injections that can go into the eye that actually fight against the molecules that are causing those new blood vessels to grow. And these are antibodies that can be injected into the eye, and they can be very effective controlling patients' wet macular degeneration.

It's been a much bigger uphill battle, even over the last decade as advances are being made to really try to knock back or slow down even the dry form of macular degeneration. There was just some exciting news, even just in the last few months. The first successful trials of a treatment for the dry form have just shown success in properly randomized, controlled human clinical trials, phase three clinical trials.

So it's an exciting time. Those new treatments are not gonna be a panacea. They slow the progression, like the anatomic progression of the disease, maybe by 20 or 25%. And so patients are still gonna get worse even with those treatments. So there's still a lot more to be done to really knock back macular degeneration.

I wanna mention, you mentioned retinitis pigmentosa. That's like an inherited form of a type of macular degeneration. It's also affecting the rods and cones and also the support cells, the RPE cells in the back of the eye. Retinitis pigmentosa is an inherited form. There are actually many different genes you could have that could lead to retinitis pigmentosa.

In aggregate, if you add up all the people with all those different genes, and it can be very devastating 'cause it can really affect the vision, knock out your vision very early in life, including in children and even for versions of that in babies. But you add that all up, it's still much less common in aggregate than macular degeneration.

But in a way, it's quite a bit more severe because it does affect people much earlier in life. So I sort of clump those together, macular degeneration, retinitis pigmentosa, degeneration of the rods and cones and the support cells, the RPE support cells. And then you can't have this part of the discussion about what are the devastating eye diseases without bringing up diabetic retinopathy, especially because diabetes, unfortunately, really continues to grow in, especially, let's say in the United States, certainly in the developed world.

As we, especially type two diabetes with eating habits, exercise habits, contributing to a proliferation of some of the risk factors for type two diabetes, metabolic syndrome, obesity, we're unfortunately seeing a proliferation, a growth in the number of people with diabetes. And with the growth in diabetes, unfortunately comes a growth of the complications of diabetes.

And one of the major complications of diabetes is damage to the retina inside the eye. And we call that diabetic retinopathy. And there again, some of the same damage that occurs, especially when in diabetes, again, some new blood vessels are growing or blood vessels are leaky. Some of that can be treated with, used to be lasers and now more commonly is often being treated with some of the same injectable drugs that are treating macular degeneration.

But there's still a lot of vision loss with diabetes and diabetic retinopathy. I think that's an area where again, early screening, making sure if you have diabetes, that's an indication where you definitely have to be going in and getting your, at least annual exam with an eye care provider or having someone take a photograph of the inside of your eye and rate that photograph to say if you have any diabetic retinopathy or not.

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