Dr. Sidney Schreiber, a cardiologist from Scarsdale, N.Y., was in his mid-70s and still working in the lab and caring for patients when he noticed that he could not see clearly with his right eye.

A visit to his ophthalmologist produced a discouraging diagnosis. Schreiber had rapidly progressive macular degeneration, and within three years he was functionally blind.

An estimated 10 million Americans have this progressive disease, though most are not as severely affected as Schreiber, and some are not yet aware that they have the painless condition. It is the leading cause of legal blindness in Americans over 55.

The numbers affected will continue to climb as the population ages, prompting a race to develop more effective treatments and perhaps even preventives, including measures based on recently identified genetic factors.

A familiar regimen

Meanwhile, there is much that people can do now to ward off this condition or slow its progress. Interestingly, the same steps that lower the risk of high blood pressure, heart disease, diabetes and some cancers can also help protect the eyes.

Though peripheral vision remains intact, macular degeneration robs people of their central vision, making it hard or impossible to read, write, drive, watch television, see the time, recognize faces and see where they are going.

Still, many who are seriously afflicted manage to pursue active lives. The late actor Don Knotts was 57 when his disorder was diagnosed, but he continued to work almost until his death Feb. 24 at age 81.

Although most patients are over 55 when found to have what is commonly called age-related macular degeneration, some develop macular disease as children or young adults. Marla Runyan was in the fourth grade when she was struck with the disease, yet she finished college and competed twice in Olympic running events despite being legally blind.

Schreiber, the cardiologist, was an accomplished artist when macular degeneration forced him to abandon his hobby and his career. He lapsed into a serious depression for nearly two years, emerging only after a visitor from Lighthouse International showed him all he could do with low-vision aids.

Encouraged by his wife, Freda, who became his eyes, he gradually resumed his favorite activities, with modifications. He visits museums (his wife reads the legends aloud), listens to recorded books, gardens (though he sometimes pulls up flowers instead of weeds) and has resumed painting.

He has even been able to put his medical training to good use. Now 84, he is scientific director of the American Macular Degeneration Foundation, which sponsors research and provides support and information. It also publishes a newsletter and has produced the helpful "Hope & Cope" DVD, both available for a $25 contribution. The foundation can be reached at P.O. Box 515, Northampton, Mass. 01061-0515 or at (888) 622-8527. Its Web site is www.macular.org.

The macula is a dense collection of light-sensitive cells in the middle of the retina along the back of the eye. These cells are used for "straight-ahead" vision. Most cases of degeneration begin as what is called the dry form of the disease. Yellow deposits called drusen form under the retina, increasing in number and size until they destroy macular cells and blur central vision.

The disorder can progress so slowly that deteriorating vision is not noticed until it is quite advanced. But as it worsens, more light may be needed to read and faces may become hard to recognize. Far less often, degeneration occurs as the wet form, leading to a rapid loss of central vision when abnormal blood vessels grow under the retina and leak blood and other fluids, raising the macula off the wall of the eye. In about 10 percent of cases, dry macular degeneration develops into the wet form.

Looking for early signs

Schreiber said, "I might have had the dry form for 10 years, for all I know. It's probably my fault for not seeing an eye doctor every year."

Which raises a critical point. Early signs can be readily detected by a thorough eye exam. People 50 and older should have such exams yearly, or twice a year with signs of disease.

Prevention and treatment

The established risk factors offer strong clues to avoiding or delaying onset of the condition. They include smoking, obesity, high blood pressure, sedentary living, overexposure to sun and a diet deficient in green leafy vegetables and fish.

Other risk factors are being a woman, farsighted or Caucasian and having light eye or skin color, cataracts and a family history of the disorder. Two factors, oxidation and inflammation, appear to cause macular injury. Studies sponsored by the National Eye Institute found that daily consumption of a high-dose formula of antioxidants and zinc could reduce the risk of early macular degeneration advancing.

Various products sold over the counter contain this formula or one like it: 500 milligrams of vitamin C, 400 I.U. of vitamin E, 15 mg of beta carotene, 80 mg of zinc oxide and 2 mg of copper. Smokers should avoid products containing beta carotene.

In addition, most experts recommend a supplement of lutein, zeaxanthin or both, carotenoids found in dark green leafy vegetables. Twinlab makes a supplement, Ocuguard Plus, that contains lutein.

Visudyne by QLT and Novartis and Macugen by Eyetech Pharmaceuticals and Pfizer have also been shown to slow deterioration of eyesight in wet type degeneration. Another drug awaiting approval, Lucentis by Genentech, may also help.

Next: Living with low vision.