Some facts about glaucoma

MILLIONS OF people worldwide are affected by glaucoma, a treatable eye disease that damages the optic nerve and causes blindness. Unfortunately, according to Joanne Katz, Sc.D., associate professor, Johns Hopkins School of Public Health, only half of those with the disorder know they have it. In its early stages glaucoma has no symptoms. If you want to keep seeing those you love, you might take some time during this week to take steps to prevent blindness by a simple eye examination for glaucoma.

Q: Dr. Katz, who is at risk for glaucoma?

Dr. Katz: Everyone is at risk. The risk increases with age and people with a family history are more at risk. Glaucoma is the leading cause of blindness among people of African or Caribbean descent, and the second leading cause among whites. African-Americans are four to five times more likely to develop glaucoma and six to 15 times more likely to go blind from this disease than other groups. The age of glaucoma onset for African-Americans is younger than in whites, so African-Americans over the age of 20 should have their eyes checked for glaucoma every three to five years. It is recommended that everyone over the age of 40 be checked for glaucoma every two to four years.

Q: Are there any other risk factors?

Dr. Katz: Besides age -- over age 35 if black, or over 60 if white -- other risk factors can include having a family history of diabetes, being very near-sighted, having had eye surgery or eye injuries or using steroid medications for lengthy periods.

Q: What is the examination like?

Dr. Katz: The examinations for glaucoma are painless. They include measuring the pressure within the eye by touching a sensitive gauge to the eye's surface and having the doctor dilate the pupil so that the optic nerve can be clearly seen and checked for damage. Dilating the pupils takes about half an hour and the vision field test takes about twenty minutes for each eye -- time wisely invested if you want to prevent blindness.

Q: How does glaucoma cause blindness?

Dr. Katz: There are several different types of glaucoma, but each type damages the optic nerve, the nerve that carries images to the brain. The damage is thought to occur from increasing pressure on the optic nerve. A fluid called aqueous humor needs to drain through channels located at the front of the eye. When a person has glaucoma, the fluid doesn't drain properly and it builds up, increasing pressure on the optic nerve and causing damage that increasingly limits sight. Loss of vision from glaucoma is a painless, slow process, with the peripheral vision slowly reducing until finally the central vision is lost. Because glaucoma is painless and slow, people don't know they have it. If untreated, the optic nerve is damaged so badly that blindness results. Early diagnosis and treatment can prevent blindness.

Q: Are there ever any warning signs of glaucoma?

Dr. Katz: For most people with glaucoma, there will be no warning signals until much of the eye has been damaged and treatment is not that effective. This is why it is so important to have a regular eye examination. In a small number of people, warning signs might include frequent changes of eyeglasses, none of which is satisfactory; an inability to adjust eyes to darkened rooms; loss of vision; blurred or foggy vision; and/or rainbow-coloured rings around lights.

Q: What treatment is available?

Dr. Katz: There are a variety of treatments, all aimed at reducing pressure in the eye. Treatment may be through medication and surgery, either laser or conventional. The patient and the doctor should decide which treatment is best. But most importantly, if glaucoma is treated early, blindness can almost always be prevented.

-- Information compiled from InteliHeath website

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