Glaucoma is one of the most undertreated eye diseases, and it causes irreversible blindness. Why is it so undertreated? Typically, it is because people do not know they have it, or they do not realize it is getting worse.
There are several types of glaucoma. In general terms, most glaucoma may be classified as acute or chronic and open angle versus closed angle. There are other subtypes beyond that basic classification, but the most common is chronic open angle glaucoma.
The good news is that chronic or primary open angle glaucoma often is slowly progressive over years, and not rapidly progressive like acute subtypes of glaucoma. The bad news is that any damage lost to glaucoma is irreversible. Once the nerve cells die, they do not grow back.
The following video, taken from an invited lecture by Dr. Bennett Walton to policy makers partnering with Prevent Blindness in Alabama, shows how the brain fills in gaps in our vision in a way that leads to dangerous situations with driving and other activities.
Typically, glaucoma results in the loss of peripheral vision first and central vision last. In this way, it is the opposite of macular degeneration, which spares peripheral vision entirely. One might think, “Oh, okay, I’ll just notice when I can’t see in my peripheral vision and see a doctor then,” but that is a bad idea.
It is a bad idea because glaucoma patients’ brains fool them. Our brains have the amazing ability to recognize patterns, and they will extend patterns as an optical illusion. Did you know we all have a natural blind spot in each eye that most of us don’t know about? Each eye has an optic nerve connecting it to the brain to send visual information. There are exercises you can do to prove it, but they are not easy.
How to find your natural blind spot by “losing” a dot in it:
- Put two dots on a piece of paper 4 inches apart, but make them horizontally and not vertically stacked.
- Close your left eye or cover it with your left hand. Hold the paper with your right hand.
- Looking only with your right eye, focus directly at the dot that’s on the left side of the paper. Keep focusing only on this left dot.
- Keeping the dots horizontal, move the paper slowly closer or further from your eye until you find the distance from your eye at which you are able to “lose” the right dot in your blind spot. It will seem to disappear!
If you were able to find the sweet spot where you “lose” the dot in your blind spot, then you have seen how the brain can be missing visual information but still make you feel like you’re seeing everything.
That’s how glaucoma works. Glaucoma patients may have the loss of some peripheral vision, but they will be walking or driving, and then they will suddenly hit something or trip because “it came out of nowhere.” Dr. Walton recalls one glaucoma patient who tripped on a stool in a hallway because he thought he was seeing the entire hallway. In reality, his brain filled in his blind spot by continuing the carpet color and linear layout, so he was fooled into seeing that the walkway was clear.
As you can tell, glaucoma is different from tunnel vision because people with glaucoma do not know they cannot see the periphery.
Thankfully, glaucoma is usually treatable, especially if caught early. It may be treated by using drops, laser, or surgery to reduce the intraocular pressure, with the goal of stopping or slowing progression of nerve damage. One of the best times to treat glaucoma is at the time of cataract surgery, because removing the cataract and replacing it with a thinner intraocular lens (IOL) often allows the drain of the eye to be more open, reducing pressure on the optic nerve. Call us at 713-893-2020 to schedule an evaluation or to learn more.