FAQ's

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Q. What causes glaucoma?
High pressure inside the eye is known to cause glaucoma. The normal eye continuously produces and drains fluid internally in order to maintain the normal shape and pressure of the eye. This normal shape and pressure is necessary for you to see properly. In glaucoma, there may be a blockage of fluid drainage or an excess of fluid production, which leads to high pressure inside the eye. If you have high eye pressure, the increased pressure may damage your optic nerve. Some people, however, are able to tolerate high eye pressure without developing glaucoma damage to the optic nerve. The reason for this is unknown. The Ocular Hypertension Treatment Study has shown that treatment of increased eye pressure reduces the risk of developing glaucoma by half for some people.

Some people develop glaucoma even without evidence of increased pressure inside the eye. In fact, recent studies show that up to 50% of people with glaucoma may not have high eye pressure measurements. For example, persons of Japanese descent are more prone to have glaucoma without elevated eye pressure, and “normal pressure” glaucoma is more common in Japan than “high pressure” glaucoma.

Many studies are in progress to discover the reason for glaucoma damage in people who do not have increased eye pressure. The two leading theories are that damage to the nerve is caused by poor circulation to the nerve, or that abnormally high concentrations of naturally occurring chemicals or hormones cause the damage.

Scientists who believe that poor circulation causes glaucoma have used special ultrasound testing to show decreased blood flow to the eyes of some people with glaucoma (• See Photo). Many of these people with “normal pressure” glaucoma also have other problems with their circulation, such as heart disease, poor circulation to their legs and feet, or hardening of the arteries.

Other scientists have shown increased concentrations of glutamate and other chemicals in the eyes of people with glaucoma. These chemicals are naturally produced by the body, and in normal amounts, help with normal eye functions. In abnormally high concentration, however, these naturally-occurring chemicals can actually harm the very nerve tissues from which they are produced. The scientists still have not discovered why the body produces abnormally high amounts of these chemicals in eyes with glaucoma.

Doctors and scientists are working to discover treatments for poor circulation to the optic nerve and treatments to decrease the concentration of these harmful hormones in the eye. Studies are under way to determine if improving circulation or decreasing the hormone concentration will help stop damage from glaucoma.

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