Retinitis pigmentosa (RP) is an eye disease that causes degeneration of the retina, the light-sensitive layer of tissue at the back of the inner eye. Photoreceptor cells called rods and cones in the retina gradually die off, causing a slow decline in vision. RP is inherited, involving a range of genetic defects. It takes several forms, but in general, night vision is affected first, as is the case with your son. Later, peripheral (side) vision declines. While retinitis pigmentosa seldom causes complete blindness, eventually central vision also deteriorates.
Unfortunately, your son’s physician is correct – there is no effective medical treatment to stop or reverse the progression of this disease, and don’t be misled by claims for products offered on the internet as cures for RP; they are unfounded.
Wearing sunglasses may help protect the retina from ultraviolet light and help slow vision loss. The only treatment that has shown some benefit in a clinical trial has been 15,000 IU of vitamin A palmitate per day. A six-year study at Harvard that included 600 patients ranging in age from 18 to 49 showed that vitamin A slowed the progression of retinitis pigmentosa by about 20 percent per year. The findings were published in the June 1993 Archives of Ophthalmology. Because high doses of vitamin A over time can lead to adverse effects, this treatment should be undertaken only under the supervision of a physician. Patients need to have their blood levels of vitamin A and liver function measured before starting therapy, and these tests will have to be repeated annually. The Harvard study also found that the disease progressed faster among patients who were taking 400 IU of vitamin E daily, although dietary amounts and smaller amounts of vitamin E in supplements didn’t adversely affect progression. The lead investigator, Eliot L. Berson, M.D., a professor of ophthalmology, warned against taking too much vitamin E and against taking doses of vitamin A higher than those used in the study. Higher doses won’t help and might cause liver disease.
There’s also some evidence from Harvard suggesting that a diet rich in omega-3 fatty acids can further slow progression of retinitis pigmentosa among patients taking vitamin A. In addition, a small study from Johns Hopkins published in 2006 indicated that lutein supplements might help a little (here, patients were not taking vitamin A and the researchers said that their findings should be interpreted cautiously).
Andrew Weil, M.D.