African Americans at High Risk of Glaucoma

African-Americans have six times the incidence of glaucoma compared to whites, according to Emory glaucoma specialist Mary Lynch, and researchers are still trying to find out why.

Not only are blacks at extremely high risk for the potentially blinding pressure within the eye that characterizes glaucoma, but they also experience more aggressive forms of the disease, said Lynch, associate professor of ophthalmology at the School of Medicine, chief of ophthalmology at the Veterans Affairs Medical Center and a council member of the Georgia Society of Ophthalmology.

She and other members of the society's governing council met with the Black Congressional Caucus of the Georgia legislature on Jan. 26 to emphasize the importance of education and early detection of glaucoma in African-Americans.

"We need to heighten awareness among members of the African-American community about this potentially blinding yet preventable disease," Lynch said. "People may have glaucoma and not know it because symptoms only become apparent once the disease has progressed. Getting a simple glaucoma test is simple -- and can be sight-saving."

Researchers do know that the racial disparity in glaucoma incidence cannot be attributed to lack of access to medical care or insurance, as is sometimes the reason for disparities in incidence of other diseases. They also know that if caught early enough, much of the vision damage associated with the condition can be stalled or halted.

Lynch and her colleagues are gathering important information on glaucoma in African-Americans through Emory's participation in two of the largest federal glaucoma studies in the nation. The Emory group has recruited more patients for the multi-center Advanced Glaucoma Intervention Study than any other participating medical center. The group also is studying patients with increased pressure within the eye who have not yet developed glaucoma symptoms as part of the Ocular Hypertension (high blood pressure) Treatment Study (OHTS). Both studies are funded by the National Eye Institute of the National Institutes of Health.

Those interested in participating in the OHTS program may call 248-4134.

What is Glaucoma?

Glaucoma is a group of eye diseases that gradually steals sight without warning and often without symptoms. Vision loss is caused by damage to the optic nerve. This nerve acts like an electric cable with over a million wires and is responsible for carrying the images we see to the brain.

It was once thought that high intraocular pressure (IOP) was the main cause of this optic nerve damage. Although IOP is clearly a risk factor, we now know that other factors must also be involved because even people with "normal" IOP can experience vision loss from glaucoma.

Different Types of Glaucoma

The two main types of glaucoma are open angle glaucoma, or primary open angle glaucoma (POAG), and angle closure glaucoma.

Primary Open Angle Glaucoma
This is the most common form of glaucoma, affecting about three million Americans. It happens when the eye’s drainage canals become clogged over time. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can’t drain out of the eye. With open angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs inside the drainage canals, like the clogging that can occur inside the pipe below the drain in a sink.

Most people have no symptoms and no early warning signs. If open angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated.

Angle Closure Glaucoma

This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is much more rare and is very different from open angle glaucoma in that the eye pressure usually goes up very fast. This happens when the drainage canals get blocked or covered over, like the clog in a sink when something is covering the drain. With angle closure glaucoma, the iris and cornea is not as wide and open as it should be. The outer edge of the iris bunches up over the drainage canals, when the pupil enlarges too much or too quickly. This can happen when entering a dark room.

A simple test can be used to see if your angle is normal and wide or abnormal and narrow. Treatment of angle closure glaucoma usually involves surgery to remove a small portion of the outer edge of the iris. This helps unblock the drainage canals so that the extra fluid can drain. Usually surgery is successful and long lasting. However, you should still receive regular check-ups. Symptoms of angle closure glaucoma may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.


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