Age-Related Macular Degeneration (Amd)

by Food and Drug Administration (FDA)

(Page 2 of 4)

The Problem:

The cause is unknown, but AMD occurs when light-sensing cells in the macula break down. The macula is the central part of the retina and is responsible for clear, sharp vision.

About 90 percent of people with AMD have what's known as the "dry" type, and the remaining 10 percent have the "wet" type. The wet type of AMD is more severe and causes the most vision loss. In the dry type, the light-sensitive vision cells deteriorate but there is no bleeding. In the wet type of AMD, new blood vessels grow and leak blood and fluid under the macula. For some people with the disease, vision is affected very slowly. But for others, the disease progresses rapidly over the course of weeks to months.

"Macular degeneration rarely leads to complete blindness, but often causes severe and irreversible loss of central vision," says Stuart L. Fine, M.D., chairman of the department of ophthalmology at the University of Pennsylvania. Side vision remains, but the center of vision, which is needed for daily tasks like reading and driving, is destroyed.

About 1.7 million Americans have some form of AMD, according to the National Eye Institute (NEI). It's the leading cause of vision loss among Americans ages 65 and over. The disease is painless, and common symptoms include blurry vision, distorted vision, such as seeing straight lines as crooked or wavy, or a dark, empty area appearing in the center of vision.

Dorothy Borne, 66, a retired food technician from Hahnville, La., was diagnosed with wet AMD and experienced blurriness in her left eye about three years ago. It presented abruptly because a large quantity of fluid leaked into the macula from abnormal blood vessels.

"When I got to work that morning, I noticed that everything looked blurry," she says. "I didn't know what was wrong."

Risk Factors:

Age and a family history of AMD are the biggest risk factors. People over age 60 are at the highest risk, and should get an eye exam at least every two years.

Fine says, "Other risk factors may include smoking, low lifetime intake of dark green leafy vegetables, high blood pressure, and cardiovascular disease. Some epidemiological studies have identified farsightedness and light eye color as risk factors."

According to NEI, women tend to be at greater risk for AMD than men, and whites are much more likely to lose vision from AMD than blacks.

Those at risk should get in the habit of checking their central vision in each eye separately by covering one eye while evaluating the other eye, Fine suggests. It is recommended that some patients keep an Amsler Grid on their refrigerator as a reminder to check their eyes at home. You look at the dot in the center of the grid to see if lines around it appear wavy or distorted, which could be a sign of AMD. Once you have AMD in one eye, there is a roughly 50 percent chance that it could occur in the other eye, so it's important to report any vision changes to your doctor and routinely test the other eye.

Studies have suggested that a diet rich in dark green, leafy vegetables such as spinach and collard or mustard greens lowers the risk of AMD. These foods are a source of nutrients such as vitamin A, vitamin C, and vitamin E. But experts say it's important to recognize that a balanced diet is generally important for eye health, the same way it is for the rest of the body.

Recent NEI research has shown that nutritional supplements — vitamin E, vitamin C, beta carotene, and zinc — may benefit some people who have advanced AMD. The American Academy of Ophthalmology recommends that if you have intermediate or advanced AMD in one eye only, you should talk with your physician about whether nutritional supplements may help you and how to take them safely. Not everybody needs supplements. For example, in large quantities, zinc can be toxic. Beta-carotene can increase the risk of lung cancer in smokers. High-dose nutrients can also interfere with medications and decrease the absorption of other nutrients into the body.

Treatment:

"For the dry form of AMD there is no specific treatment other than low vision rehabilitation, which shouldn't be underestimated," says Fine (see "Low-Vision Resources").

The biggest advance in AMD treatment so far was the approval in April 2000 of Visudyne (verteporfin for injection) for treatment of the classic type of wet AMD. About half of those with wet AMD have the classic type. Visudyne is manufactured by QLT Photo Therapeutics Inc., Seattle, and marketed by Novartis Ophthalmics, Duluth, Ga.

Visudyne can't restore vision that's been lost, but it can slow the loss of vision from AMD. It's injected into the patient's arm and it travels to the abnormal blood vessels in the eye. Then a laser is aimed at the patient's eye for a little over a minute to activate the drug. The drug works to stop or slow blood leakage. Common side effects include light sensitivity and reactions at the injection site.

Some cases of wet AMD can be treated with laser surgery. Again, lost vision usually can't be restored, but the laser aims a light beam onto new blood vessels to destroy them to preserve what central vision remains. Borne had laser surgery immediately and ended up having several more surgeries in the span of a few months, which left her with some scarring in the eye. "She needed the surgeries because some of the blood vessels around the macula continued to bleed," says Monica L. Monica, M.D., Borne's doctor and an ophthalmologist in New Orleans.

In the end, the laser surgeries stopped the bleeding. "If the hemorrhage isn't stopped, there could be even more extensive loss of vision than just central vision," Monica says.

Borne has lost central vision in her left eye, but still has side vision in that eye and can grossly see large objects like cars.

Borne, who can still see clearly out of her right eye, says, "I can read, just not for very long. After a while, words start jumbling together." She knows that if her right eye bothers her, day or night, she should call her doctor right away. "I just hope my right eye will stay OK," she says.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.