A conversation on Glaucoma - With Dr. Chinichian
We'll start off here with glaucoma. The definition is ... Glaucoma is a condition of increased pressure within the eyeball causing gradual loss of sight due to damage of the optic nerve. There are two types of glaucoma, open and closed angle, and I will be discussing those, as well.
Starting off with some facts about glaucoma, glaucoma is one of the leading causes of blindness. There are not always symptoms to glaucoma, and that's what makes it kind of tricky because you could be walking around with glaucoma, you or a family member, and only when you have screenings with your optometrist or ophthalmologist would you be able to know that you actually have glaucoma. That's why annual eye exams and things like that are important. As of now, there's no cure to glaucoma. We do have treatment options, which I will also be discussing further in the lecture. Half the patients with glaucoma do not have high eye pressure, so that seems kind of confusing, as well, but the actual cause of glaucoma ... We don't know all of the causes, and so this is kind of a mystery in the disease that we're learning a lot about as the years go on.
A fact about pressure in the eye, eye pressure rises and falls throughout the day, so if you can imagine if you have pressure that can go up and down throughout the day, if you come see the eye doctor when the pressures are up here, he may think something different than when you come in at the time of the day when the eye pressure is down here, so it's kind of an overall picture. With glaucoma and just with regular screenings, we can sometimes catch it when it's at the high part, which flags our attention to take care of it or look into it.
Here are some of the risk factors for glaucoma. Number one, having high intraocular pressure, which is something that we talked about, having this high pressure in the eye. Being over age 60. African-American or Hispanic ethnicities have a higher risk, it is a risk factor for glaucoma. Having a family history of glaucoma. There are genetic factors to glaucoma so, if you have a mother or a grandmother or a brother or sister who have glaucoma, that's all the more reason to go in and get checked or have a screening done for your eyes.
Having other medical conditions such as diabetes, high blood pressure, heart disease, sickle cell anemia, these are all things that affect your general health. You can imagine, if you have a condition that's damaging the optic nerve, if it's not getting good blood flow from, say, diabetes or high pressure from high blood pressure, these are the type of things that affect your whole body so they also worsen or can cause glaucoma to be worse, as well. If you're taking corticosteroid drugs. Steroid drugs are used after cataract surgery and things like that. Someone who's on these drugs for a long period of time can get spikes in eye pressure, which can cause glaucoma, as well.
We're going to start off here with the anatomy of the eye. This is a cut-through of the eye, kind of from front to back, with the top of the eye being toward the top of the screen and the back of the eye, the optic nerve, and the brain being back down here. Glaucoma and the whole pressure system of the eye, the pressure system of the eye is up here, where you have the cornea, which is this clear covering of the eye where LASIK is usually done, things like that, you have the iris, and you have the lens. This is the lens that's removed during cataract surgery, which is right behind the pupil. The pressure in the eye is made right here. It's called the ciliary body. Eye pressure is made here. It works its way and it floats and it kind of goes out through the angle of the eye. This is the angle right here, which you may hear open angle and closed angle, which we'll discuss.
If you have a lot of pressure building up up here in the front portion of the eye, this will push downward onto the jelly part of the eye, which will in turn push onto the optic nerve, which is right here. This is where all the information, all the nerve information comes together into a bundle, becomes the optic nerve, and it goes back to the brain to become processed. This whole system kind of works to hydrate the eye and give nutrients but also, if the pressure is too high, then you get a compressive effect on the nerve.
Let's talk about the water system of the eye. This is a close-up of the front portion that we discussed and discussing how you could have open or closed angle. The more common type of glaucoma is this open angle, this picture here on the left. You can see here that, kind of from the description that we talked about, the fluid in the eye is made right here. You can see with the arrows, it follows and works its way toward the angle. You can see in this diagram here, the angle is nice and open. There's a nice big angle between here and here.
Now, on the opposite spectrum is someone who has a closed angle glaucoma. The ... You see the iris here, this red structure here is pinching off the drain. What happens is the lenses move forward, the water can't get out, and, just like your sink if you put your hand over the drain or a plate goes over the drain, water pressure is going to elevate quickly. Now, closed angle can happen suddenly. You may hear this happen to some people, where sudden severe eye pain and blurry vision and the pressure spikes up very high. Same thing in your sink analogy where, if you were to put a bunch of things over the drain and the water faucet is still on, it's going to build up and overflow and cause this pressure system.
In open angle glaucoma, the problem is more downstream. It's not that the water can't get to the drain, it's that the drain is either not flowing quick enough or something further downstream that's causing the build-up of the fluid.
Just like I kind of showed you in that other picture here, all of the pressure that happens in the front of the eye pushes on the jelly of the eye, which pushes on the nerve, which causes damage to the optic nerve. This is important because all of this information has to come and make its way back to the back of the brain, but, if you're pushing on it for a long period of time, it's not going to ... It's going to start to have damage.
Think of it like your arm. Sometimes, you sleep on your arm and it goes numb. You do it for an hour, no problem, you shake it off, you go back to normal, but, if you were to sleep on your arm for days and days and days or years, you can imagine it's not going to quite be the same that it used to me. That's kind of the same thing with the nerve in the back of the eye where, if it's having pressure on it for a long period of time, it's going to start getting damage and stop working the way it's supposed to work. This is why the general screenings for checking eye pressure and checking the nerve are important.
Here's a picture of the optic nerve when we look into the back of the eye. It's not the best picture, but I'll try to outline it here for you. What you see is an orange circle and a yellow circle, kind of a lighter inner circle. This is a normal optic nerve here on the right-hand side. You can see that ... Well, you can't really see very well in this picture here, but imagine you have a doughnut with an outer edge and an inner doughnut hole. The space between the doughnut hole to the outer edge is the doughnut. That's the nerve tissue. You can see in this picture here on the left that this doughnut hole is very big. If you have a lot of doughnut hole, you don't have a lot of doughnut, which is the nerve tissue. These are the things that your doctor sees when he looks in the back of the eye. If he sees a nerve that looks like this, he starts thinking, "Hey, there's probably some glaucoma going on. We need to find out why it's like that, why the nerve looks larger than it should be."
Here's another. Here's a computer, a test that we do called an OCT, which measures that. Like I said, there was a doughnut and a doughnut hole. Let me show you the difference here. In that previous picture, the picture on the left was the damaged one. That kind of matches here. You can see in this picture right here there's a red circle and a black circle and it's like a doughnut hole. You can see that this nerve, which is the person's left nerve versus their right side here, you can see the doughnut hole is much bigger on this side. If we look at the numbers here, the thickness or, as you can say, the thinning of the nerve, this is in the green. This is 100, this is 64. There's definitely a difference in this person's optic nerves, where there's thinning on this side and this side is more normal. This is one piece of information that we use to detect glaucoma.
The second piece of information is, "All right, so, yeah, we have a thinning nerve, but what does that mean for the information that's getting to the brain? Is there damage? Just having something that's shaped a certain way doesn't mean it doesn't work as well." Excuse me ... Here's a test that we do called the visual field test. Some of you even may have taken it where ... Then, they put you in this half-circle and you push a button every time you see a light. Each one of the little light dots makes a map. This is the map of your vision when you look out into the world. This is a visual field done of the right eye, and this is a normal test here. You can see this spot right here is the blind spot. We all have a normal blind spot. Everything else on the outside looks fairly white, meaning the patient is seeing it. Black means you don't see it.
Here on this diagram, you can see, "Hey, well, there's something going on here on this outside here that's not present in here. There's some darkening or some decrease in your peripheral vision in this eye." Peripheral vision is not something that you use 100% of the day. You use your central vision to read, to watch TV, to do all those things. Your peripheral vision kind of works to get your attention, and then you turn your head or move your eyes to look at it. When you lose your peripheral vision, you don't notice it as much. That's what makes glaucoma tricky, in that you could be losing peripheral vision more and more and more and not know it until it's too late. This is where the, like I said, the importance of the eye exams comes into play.
How do we treat glaucoma? We know that there's no cure for glaucoma so, just like high blood pressure or diabetes, we have different medicines to take care of it. The medicines come in the form of an eye drop. Goes right to the source, right on top of the eye where it needs to work. The drops that we have here, these are the individual drops. There's four different types. Some of them come in combinations. For example, a combination of yellow and orange may make a medicine or purple and yellow make a medicine that your doctor may give you.
Now, these drops work on either the drain, making the drain bigger or helping the flow, or they work on the faucet, where they decrease the flow of the ... The creation of the water. They work in different ways and they work together. When you have glaucoma, typically your doctor starts you on one medicine and then, if that stops working over the years, they add a second one and a third one. It's a lifelong medicine that you ... They're cumulative. We keep adding on the medicines as needed.
Another procedure we can do is what's called stent, an eye stent, where this little device here ... This is one millimeter in size. I know it's much bigger here on the screen but it's very, very small. This little snorkel here is surgically put into the drain to lower the pressure. It's like a little side port so water can get into the drain much quicker.
Now, when all of these fail, when the drops fail or we can't get your pressure controlled, then we need to think about creating a new drain where ... We've just got to get the water out the eye in a whole different way. That's this here, with a shunt. You can see here there's a little device that's sutured to the outside of the eye, to the white part of the eye, with a little tube that comes right into the front part of the eye. These tubes are very small. You wouldn't see them unless you paid really, really close attention. Your doctor would manage these and do a tube shunt surgery if your pressure is not controlled.
Glaucoma is a very slow disease which is because technology and research is always evolving. Things that may come down the line, the things that the different researchers are thinking about and working on, one of them is potentially an implant. Now, if we can put a little implant in your eye that has the medicine in it and it slowly releases a little bit of medicine at a time, that would be better because you wouldn't have to forget your drops or not get the medicine. We would know that it's working for you and that you're getting all your medicines. Or, in a contact lens form, which is something that some researchers are thinking about. You can put a contact lens in every day, or the ones that you normally wear, to have medicine it. Hey, that would save you a step and not needing another medicine.
We talked about the micro shunts, which was that little picture, that little snorkel. There's different versions of that that are coming out that they're doing research on, that ... Say if it's now a cataract surgery where you're going to have surgery anyways, we can put these micro shunts in to lower the pressure. You wouldn't need a separate surgery, we'd do it at the timing of a surgery that we were already going to do.
Like we talked about, glaucoma is genetic so, if we can tackle to problem at the source, meaning your genes and how your body is designed, we can prevent it from happening in the first place.
Lastly, stem cell research is something that's going on in a lot of different fields. Glaucoma is a progressive disease that damages the nerve of the eye. As you know, nerves don't really regenerate very well so any damage that's incurred from glaucoma, we can't get back. If we can regenerate the nerve or use stem cells to regenerate the nerve, then that would be a potential cure for the problem.