Dr. Guy Eakin: Today, I am going to talk about glaucoma, the leading cause of irreversible vision loss and ultimately blindness. Glaucoma, although commonly referred to as one disease is actually a group of eye disorders.
What each of these different types of glaucoma has in common is that each leads to damage of the optic nerve which is the bundle of nerve fibers that carry information from the eye back to the brain. Damage to the optic nerve can lead to vision loss and ultimately to blindness.
Many people believe that Glaucoma is defined as having elevated pressure inside the eye however elevated pressure alone does not define the disease; instead elevated eye pressure can be thought of as a leading risk factor for the development of the disease.
So to understand how the eye pressure impacts, the development of glaucoma, it's important to understand how the eye works. The eye constantly makes a fluid called aqueous humor which helps maintain normal eye pressure and provides nutrients to the cornea and the lens of the eye.
The aqueous humor circulates inside the front of the eye and primarily drains through the porous structure called the trabecular meshwork. You can think of the trabecular meshwork as being similar to the drain holes are great in your shadow. Normally, there is a balance between the amount of fluid made and the amount that leaves the eye. If this balance is not achieved, then pressure builds up inside the eye similar to a sink that backs up when the drain is blocked.
This pressure increase may eventually cause damage to the optic nerve and loss of vision. It's this characteristic damage to the optic nerve and vision loss that defines glaucoma. However, it depends on the type of glaucoma you have as to what is actually happening in your eye. There are many different types of glaucoma. The most common type of glaucoma is open angled glaucoma. The majority of the other types of glaucoma are closed angled glaucomas which can be chronic or acute.
Open angled glaucoma has no symptoms in the beginning however is a progressive disease characterized by optic nerve damage. High eye pressure is the most significant recognized risk factor for the development and progression of the disease. Although glaucoma can occur in people with normal eye pressure, as the pressure gradually builds and is left untreated, the optic nerve accumulates damage resulting in the loss of peripheral or side vision and without treatment; the result will be total blindness.
Closed angle glaucoma comes in two forms, acute and chronic. Acute closed angle glaucoma is a sudden medical emergency that must be treated immediately because blindness can result in a very short amount of time. The most common type of angle closure is known as papillary block. In papillary block the normal flow of the aqueous humor from an organ called the ciliary body to trabecular mesh or that we talked about earlier is blocked when the iris and lens touch.
Symptoms may include severe pain, nausea, vomiting and blurred vision. The patient may also see colored halos around lights. Chronic closed angle glaucoma progresses slowly and can produce damage without symptoms similar to open angle glaucoma. As I mentioned earlier sometimes glaucoma can occur when pressure inside the eye is normal. This condition is called normal tension glaucoma. The causes of optic nerve damage when the pressure is normal are not well-understood. Thus there is a need for more research into the causes and treatments of specific types of glaucoma.
There are however some known risk factors for normal tension glaucoma. So these include cardiovascular disease, high blood pressure, having a family member with glaucoma, or being a female or being of Japanese ancestry. It is important to remember that glaucoma is actually several diseases with different prognosis and treatments. The only way to know if you have any of these types of glaucoma is to visit your doctor.
Only through a thorough eye examination will an accurate diagnosis be made and sight saving treatment can be prescribed. If you want to learn more about glaucoma, check out our other videos include understanding your risk factors.