Glaucoma — Blindness?

Originally Published: October 11, 1996
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Dear Alice,

Does glaucoma cause blindness if not treated in its early stages?

Dear Reader,

Even when treated, glaucoma can cause blindness. Treatment, however, significantly lowers the risk of glaucoma resulting in blindness. Glaucoma is a disease of the eye that involves enough of an increase in interocular pressure so as to damage the retina and optic nerve. A clear watery fluid called "aqueous humor" normally bathes and cushions the eye. When this fluid is not able to drain properly through a mesh-like pathway formed by tiny ducts in the eye, then pressure inside the eye rises.

This pressure build up can happen in a few different ways. An immediate blockage of the drainage ducts will cause interocular pressure to rise a great deal in a short amount of time. This is known as acute glaucoma, a rather rare form of the disease. More common, however, is chronic glaucoma, in which the drainage ducts slowly become clogged. In chronic glaucoma, the pressure builds gradually, making it difficult for the person to detect anything is wrong. The first signs of chronic glaucoma include seeing halos around lights, or gradually losing peripheral vision (which can lead to the effect of "tunnel vision"). A few other types of glaucoma---secondary, post-surgical, and normal-tension---exist. Because of their rarity and similarity to the other two types, Alice will not describe them.

In most glaucoma cases, the increased pressure will lead to a pinching of the blood vessels that supply the optic nerve; the optic nerve is therefore "starved," and parts of it slowly begin to die (over the course of several years). In order to stop this optic nerve starvation, interocular pressure must be reduced. For acute glaucoma, medications are usually given first to relieve the pressure. Laser or conventional surgery, to make the outflow ducts wider, is also performed in most of these cases. The treatment for chronic glaucoma typically involves only medications---eyedrops, pills, ointments/gels, or wafer-like eye inserts. Surgery is necessary in about 10% of chronic glaucoma cases.

Glaucoma usually develops after the age of 40, although it sometimes affects infants and toddlers. The disease often runs in families---parents may be genetic carriers of glaucoma. Between two to three million Americans over the age of 40 have glaucoma, but only half of those people are aware of it. By the time most people sense a problem, their vision may have already been affected. For this reason, glaucoma is often referred to as the "sneak thief of sight." Approximately 5,350 people in the United States lose their sight to glaucoma each year.

Since early diagnosis and treatment do not guarantee that you will not lose your sight, it's a good idea to be tested for glaucoma regularly, especially after turning 40. Only ophthalmologists and optometrists can test for glaucoma by measuring interocular pressure and checking for optic nerve damage, among other things. If you have more questions about glaucoma or general eye health, you can call the Prevent Blindness Association at (800) 331-2020.