Glaucoma

VOL 101 / NO 5 / MAY 1997 / POSTGRADUATE MEDICINE

Glaucoma is a "silent thief." At first it causes no vision problems, but all the while it is robbing you of sight that you will never get back.

What is glaucoma?
Think of your eye as a fountain, with fluid constantly circulating to nourish the tissues and maintain the eyeball's round shape. Glaucoma is a "clogged drain" in this delicate system. In chronic open-angle glaucoma (by far the most common kind), the fluid drains away too slowly (figure 1), which raises pressure within the eyeball and eventually damages the optic nerve. In acute angle-closure glaucoma (a less common type but a real medical emergency), drainage becomes completely blocked and pressure builds up very quickly.

What are the signs of glaucoma?
Chronic glaucoma progresses very slowly. Often, the first sign of trouble is reduced side vision. Other indicators may include blurred vision, seeing colored halos around lights, adjustment problems on entering a dark room, and repeated difficulties that new eyeglass prescriptions do not help. Acute glaucoma comes on suddenly, causing severe eye pain and nausea and vomiting along with these vision problems.

Can glaucoma be treated?
Yes, and the earlier the better. Both pills and eyedrops are available to reduce pressure in the eye: Some improve drainage and some slow production of fluid. These medications must be taken faithfully every day for life. Sometimes laser surgery is used to enlarge drainage pathways. For an attack of acute glaucoma, surgery to create an artificial drainage channel may be necessary.

Can glaucoma be prevented?
No, but it can be detected before it causes serious damage. People of African descent are at especially high risk: Glaucoma occurs more often and at a younger age and progresses more rapidly in blacks than in whites. Other risk factors are diabetes, past eye injury, family members with glaucoma, extreme nearsightedness or farsightedness, and long-term use of steroid medications.

The best way to protect your eyes is to visit a doctor regularly for a thorough eye examination (about every 2 years after age 40, depending on your risk factors). Don't put off scheduling an examination, because if left untreated, glaucoma will rob you of your sight entirely.

Testing for glaucoma The procedure that is usually used to test for glaucoma is called tonometry. First, drops are put in your eyes to numb them. Then the doctor presses the tip of the tonometer against your eyeball. The instrument measures the resistance of your eye, which indicates intraocular pressure. Glaucoma raises intraocular pressure, which results in damage to the optic nerve and loss of vision.

This information is not a substitute for medical treatment.

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