Catching macular degeneration early. (Ophthalmology).

Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly in the United States. By gauging the eye's capacity to adapt to darkness, neuroscientist Gregory R. Jackson and his colleagues at the University of Alabama in Birmingham may have discovered a way to spot the earliest stages of the disease. Physicians might one day use the technique to predict whose vision is likely to become impaired.

Darkness adaptation occurs, for example, when a person walks into a dim movie theater from a bright street. In an earlier study, Jackson and his colleagues compared 20 people with early-stage AMD and 16 without the disease. In a laboratory test, the AMD patients took significantly longer to adjust to darkness than the others did.

In a new study, the researchers randomly selected examination data collected 4 years earlier from 20 elderly people who had had normal vision at that time. Fourteen of these people had reported trouble adapting to darkness; the other six had reported no such difficulties.

Recent re-examination of the eyes of all 20 people revealed that 12 of the 14 people who had impaired darkness adaptation now have AMD, while only 1 of the 6 who had reported no darkness adaptation problems has developed AMD.

The findings may help scientists searching for causes of AMD and could lead to a noninvasive test for early detection of the condition--an advance that Jackson says would be particularly useful in clinical trials designed to test new treatments.

--N.S.