Dr. Guy Eakin: Today, I'm going to talk about glaucoma, the leading cause of irreversible vision loss and ultimately blindness.
Worldwide, there are an estimated 70 million people who are visually impaired due to glaucoma and an estimated 7 million people are blind.
Before I begin discussing what glaucoma is, let me tell you a little bit about myself. I have a doctoral degree and many years of experience in research at two of the nation's top research centers.
BrightFocus Foundation is dedicated to funding research and providing free information to the public about glaucoma as well macular degeneration and Alzheimer's disease. There is helpful information available on the website at https://www.brightfocus.org.
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 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 humour which helps maintain normal eye pressure and provides nutrients to the cornea and the lens of the eye. The aqueous humour circulates inside the front of the eye and primarily drains the vaporous structure called the trabecular meshwork.
You can think of the trabecular meshwork as being similar to the drain holes or grate in your shower. 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-angle glaucoma. The majority of the other types of glaucoma are closed-angle glaucomas which can be chronic or acute. Open-angle 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 pupillary block. In pupillary block, the normal flow of the aqueous humour from an organ called the ciliary body to the trabecular meshwork, that we've 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've mentioned earlier, sometimes glaucoma can occur when the 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 prognoses 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 treatments can be prescribed.
This content was last updated on: July 29, 2015