A study conducted by the National Eye Institute and published online in the American Journal of Ophthalmology revealed that AIDS patients are four times more likely to develop intermediate-stage macular degeneration than people who do not have AIDS. The reason for this increased risk is not known. Researchers examined 1,825 AIDS patients ranging in age from 13 to 73 at 19 locations in the U.S. between 1998 - 2011. The researchers compared retinal photographs to the retinal photographs of patients within the same age range who did not have AIDS that participated in the Beaver Dam Offspring Study. Researchers discovered that the occurrence of the intermediate-stage macular degeneration in those with AIDS was almost 10 percent and after adjustments were made for age differences, it came out to be almost four times the risk. There was no evidence that the prevalence was related to any drug used in treating AIDS. The researchers believe that the immune system of an AIDS patient plays a significant role in the development of macular degeneration.