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This is the VOA Special English Science Report.

A new study shows that large amounts of vitamins and minerals can slow the loss of sight linked to aging. The condition is called age related macular degeneration or A-M-D. The disease is a major cause of blindness among old people. Doctors do not know what causes it.

The disease destroys the central part of the retina, the cells at the back of the eye that gather light. The first sign of A-M-D usually is a loss of visual clearness. People with the disease have trouble reading, driving and recognizing faces. They cannot see clearly through the center of their eyes. They must look at things from the sides of their eyes. Over time, A-M-D can cause blindness.

The National Eye Institute carried out the six-year study. Almost five-thousand people in eleven areas of the United States took part. They were between the ages of fifty-five and eighty. Some of the people had more severe forms of the disease than others.

The researchers tested a combination of large amounts of vitamins and minerals. Some people in the study were given the mineral zinc. Others took the vitamins C, E and beta-carotene. A third group received both the zinc and the vitamins. The remaining people took inactive substances called placebos.

The people in the study were in three groups, based on the severity of their disease. The researchers compared the vision abilities and other conditions of the patients after five years of treatment. Their findings were published in the Archives of Ophthalmology.

The scientists say the combination of vitamins and zinc had no effect on patients with the least severe form of A-M-D. However, they say the vitamins and zinc helped people with more serious A-M-D. The treatment cut the risk of developing the most severe form of A-M-D by about twenty-five percent. The vitamins and zinc also prevented some vision loss for those patients already suffering severe A-M-D. The patients taking zinc or vitamins separately also were helped but not as much as those taking both. Earlier studies had shown that people who eat large amounts of fruits and vegetables containing important vitamins are at lower risk of developing the eye disease.

This V-O-A Special English Science Report was written by Caty Weaver.