Edgar Degas painted with it. Victor Borge entertained with it. Sam Snead golfed with it.

These famous folks had age-related macular degeneration (AMD) -- the top cause of legal blindness for people older than 50 in the western world, the AMD Alliance International says. AMD afflicts 25 million to 30 million people worldwide.

AMD affects the macula, the central part of the retina. The retina is at the back of the eye. It contains cells that change light into nerve impulses that go to the brain. The brain interprets these impulses as sight. Damage to the macula causes a loss of central vision, critical for reading and fine detail work, but leaves peripheral or side vision intact. AMD usually affects both eyes, but one may be affected before the other. The disease often starts as blurry or wavy images, trouble picking out colors, or dark or empty spaces in the center of vision.

Two forms

AMD comes in two forms, wet and dry. Wet AMD affects about 10 percent of people with AMD. It occurs when new blood vessels grow underneath the retina and begin to leak fluid into the macula. Wet AMD causes rapid loss of central vision and poses the most chance for severe sight loss. In dry AMD, the cells of the macula gradually break down. Waste products from this breakdown form yellow fatty deposits that build up on the macula. Dry AMD causes gradual loss of central vision.

Wet AMD can sometimes be treated with laser therapy. The laser seals the leaking blood vessels to prevent further damage. Two drugs have been approved by the Food and Drug Administration to slow or block the growth of new blood vessels, thus preserving sight. Both are injected into the eye. They are Pegaptanib, a drug that is injected every six weeks and Ranibizumab, which is injected monthly.

The risk for vision loss from dry AMD may be decreased by taking a vitamin and mineral supplement that contains zinc, lutein, vitamins A, E and C. Talk to your health care provider about the risks and benefits of this treatment.

People with AMD can live productive lives that may include driving, reading and other sight-related activities, says Bruce Rosenthal, O.D., chief of the Low Vision Program at New York's Lighthouse International and author of Living Well with Macular Degeneration.

AMD patients can find special training through groups such as Lighthouse International. For instance, those with vision loss can learn how to travel through the city, how to cook and how to label clothes.

Since state laws vary, Dr. Rosenthal suggests you check with your local motor vehicle department to learn the rules on driving with partial sight.

Learning to cope

A lot of tools can help folks with AMD stay independent.

Light plays a key role. "People with AMD have serious problems with contrast," Dr. Rosenthal says. Sometimes words don't stand out enough on the page for AMD patients to see them. "LED, or light-emitting diode systems, provide better illumination for people with AMD." You can buy LEDs -- similar to lamps but with a stronger output -- at low-vision centers or through your eye doctor.

Dr. Rosenthal says handheld or stand-mounted magnifiers let AMD patients read, watch television or do any other sight-related chore.

"When you're looking at the print on a page, parts of words may be missing, or whole words are missing. In order to see that [missing part] again, you can magnify the words and enlarge the print by using special strong lenses." Mouse-type magnifiers let patients roll the mouse over the words and see them on television sets.

Closed-circuit televisions (CCTs) act as super-magnifiers, says Alexander Brucker, M.D., a University of Pennsylvania ophthalmology professor. "It's a television screen mounted on a stand," he says. "You place a book underneath it and it magnifies the image and covers the whole screen." Dr. Brucker says CCTs magnify 48 times normal size. Handheld devices can magnify up to eight times.

Dr. Brucker says people with AMD can buy software that will enlarge the print on a computer monitor so they can still use the computer. "It's extremely helpful to the visually impaired individual who wants to maintain an independent lifestyle."

Diet may also affect AMD. A study by the National Eye Institute (one of the National Institutes of Health) looked at people with moderate to advanced AMD who faced a high risk for worsening cases. One out of four benefited from taking antioxidants, says Dr. Rosenthal. Their vision did not improve, but it did not worsen. He suggests those with AMD talk with their eye doctors about vitamins and supplements.

it is important for people with AMD to check vision in each eye every day to monitor for changes in central vision.

What you can do

To help prevent macular degeneration:

• Get regular eye exams. You should have an eye exam at least every two years, but more often if you have a family history of eye disease, diabetes, hypertension or other condition that can affect the eyes.

• Stop smoking. The AMD rate doubles among smokers.

• Wear sunglasses that block 100 percent of UV rays. The sun can cause damage to the macula.

• Eat a diet high in dark green leafy vegetables such as spinach. 

To help cope with macular degeneration:

• Schedule regular visits with an ophthalmologist or retinal specialist.

• Increase lighting levels. People with AMD have problems with contrast.

• Seek training. Despite vision loss, you can stay active.

• Find tools that make the most of your vision. Magnifiers, clocks and phones with large numbers, closed-circuit televisions and computer software can help.

Common signs of macular degeneration

• Colors are harder to tell apart.

• Vision decreases in one or both eyes.

• Vision blurs.

• Waves, lines or empty spaces show up in the field of vision.

• Straight lines or objects appear wavy.

• A dark patch appears in the middle of words you are trying to read.

• Reading becomes tougher. Words seem to vanish in the middle of sentences.