Various insults, including visible light and normal metabolic processes, can lead to the production of reactive oxygen species, including free radicals, which can damage DNA and cells, and are thought to play a role in the aging process. The retina, with the presence of unsaturated fatty acids in the outer segment membranes, is a set-up for oxidative damage in the presence of light, she said. The theory is supported by basic science research, clinical epidemiologic studies, and one randomized trial, she said. In one study, animals fed diets deficient in vitamins C and E had retinal changes from bright light, and animals supplemented with these nutrients had less damage. Animals with drusen have had higher estimates of lipid per oxidation compared with animals without drusen.
Some studies suggest a beneficial role for lutein derived from foods.
Seddon said that until results of ongoing studies, like the randomized clinical trial on ARMD disease, are released, she recommends a good, healthy diet rich in fruits and vegetables and low in fat, similar to that suggested for cardiovascular disease. The hope is that perhaps, in the future, there will be specific foods and supplements for vision as well as for life, she said. The fact is that we really don t have a lot to say on this subject right now. The information that we have basically comes from observational studies, except for one small clinical trial that I would view more as a pilot study than as a definitive clinical trial, and these studies are for hypothesis development. There are major problems with uncontrolled bias and confounding, he said.