Macular degeneration

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VOL 113 / NO 5 / MAY 2003 / POSTGRADUATE MEDICINE

You've noticed that your eyesight isn't what it used to be. For many people, activities such as reading, writing, and driving get more difficult with age. Age-related eye diseases, such as glaucoma and cataracts, are becoming more common as we live longer. Another eye disease that occurs frequently but is less well known is macular degeneration, which affects more than 10 million people in the United States.

What is macular degeneration?

This condition occurs when the central part of the retina, which is called the macula, gradually begins to fail. The retina is the part of the eye that senses images and sends them through the optic nerve to the brain. The macula controls the central part of our field of vision and allows us to more clearly recognize faces and colors and see details.

Macular degeneration can occur in one or both eyes, although people who have it in only one eye are likely to have it develop in their other eye as well.

Two types of macular degeneration can occur in adults: "dry" and "wet." About 80% to 90% of people with macular degeneration have the dry form, in which the macula thins and dries and yellow deposits called drusen (drew-zen) accumulate underneath. The remaining 10% to 20% have the wet form, in which new blood vessels grow under the retina and macula and leak fluid. This type, which usually occurs in people over age 60, can lead to the most severe vision loss due to macular degeneration.

Another form of macular degeneration, which is called Stargardt's disease, can affect people 6 to 20 years old. This type usually is passed down from parents to their children.

What causes macular degeneration?

No one knows what causes macular degeneration, but some cases are believed to be related to diabetes, head injury, poor nutrition, use of certain medications, or infections. What is known is that this condition occurs more commonly in people with blue eyes and light skin. In addition, the wet type may be related to severe nearsightedness.

How is macular degeneration detected?

Many people with this condition have symptoms that lead them to visit their eye doctor. These symptoms include a blurry or "whiteout" area in the center of their vision or colors that seem "off" or more dim than usual. Some people don't realize their vision is failing until their eye doctor mentions it during a regular visit. The doctor may notice new blood vessels in the eye or drusen under the macula.

Your doctor probably will test your color vision and have you look at a checkerboard chart called an Amsler grid to see if the straight lines in the pattern look wavy to you--a symptom of macular degeneration. He or she may also ask you to take a test called fluorescein (flow-res-in) angiography, in which dye is injected into a vein in your arm and watched as it passes through the blood vessels in your retina.

Will I lose all of my vision?

Many people with macular degeneration do become legally blind. However, many who have poor central vision can still perform daily tasks, although they may eventually need help with some activities. In some cases, vision loss slows or even stops progressing for several years.

How is macular degeneration treated?

There is no cure for macular degeneration, but depending on its type and severity, your doctor may try several methods to slow the disease. Getting better control of high blood pressure with drugs or changes in diet may help keep the disease from worsening. People with the wet form may benefit from laser surgery.

Another step that may be helpful is eating more dark green leafy vegetables, such as spinach and collard greens. These vegetables contain yellow pigments called lutein and zeaxanthin, which may help protect the macula from light damage. Some physicians recommend supplements that contain vitamin C, vitamin E, and lutein. Wearing dark glasses while in the sun and not smoking may help keep the disease from getting worse. Some people may also benefit from using low-vision aids, such as large-print reading materials and extra reading lights, and by trying techniques to make the best use of the vision you have left.

For further information on macular degeneration:

AMD Alliance International
1314 Bedford Ave, Suite 113
Baltimore, MD 21208
877-263-7171
http://www.amdalliance.org

National Eye Institute
2020 Vision Place
Bethesda, MD 20892-3655
301-496-5248
http://www.nei.nih.gov

Prevent Blindness America
500 E Remington Rd
Schaumburg, IL 60173
800-331-2020
http://www.preventblindness.org

For further information on low-vision programs:

American Foundation for the Blind
11 Penn Plaza, Suite 300
New York, NY 10001
800-232-5463
http://www.afb.org

Lighthouse International
111 E 59th St
New York, NY 10022
800-829-0500
http://www.lighthouse.org

This information is not a substitute for medical treatment.

Please send technical questions related to the Web site to Ann Harste