An extensive NIH-supported study has found that low-intensity laser treatment, thought to be possibly beneficial in slowing or preventing the loss of vision from age-related macular degeneration (AMD), is ineffective in preventing complications of AMD or loss of vision. This is the major conclusion of the Complications of Age-Related Macular Degeneration Prevention Trial (CAPT), a research study of more than 1,000 people that will be published in the November 2006 issue of the journal Ophthalmology. The study was supported by grants from the National Eye Institute (NEI) of the National Institutes of Health (NIH).
The presence of yellowish deposits under the retina, called drusen, is the first sign of early AMD. Eyes with large drusen are at increased risk of progressing to advanced AMD, with accompanying loss of vision. First considered in the 1970s, low-intensity laser treatment has been shown to reduce the extent of drusen. However, the studies evaluating the impact of laser treatment on vision have been small, and the results inconsistent.
This study was designed to assess the safety and effectiveness of laser treatment in preventing vision loss among people with large drusen in both eyes. It found there was no difference in vision or in progression to advanced AMD between treated and untreated eyes, which were closely observed for the duration of the trial.
“AMD is the leading cause of vision loss in the United States for people over age 60,” said NEI director Paul A. Sieving, M.D., Ph.D. “This is an important study because after 35 years of inconsistent results from preventive laser treatment trials, we now know that this approach does not seem to stop vision loss from AMD. Doctors using this technique should reconsider its use in patients with good vision, such as those studied in this trial.”
“At present, the only established way to decrease the risk of vision loss in people with large drusen (early AMD) is to take daily supplements of vitamins and minerals as used in the NEI-supported Age-Related Eye Disease Study (AREDS),” Sieving continued. “This study found that high-dose antioxidant vitamins and minerals (vitamins C and E, beta-carotene, zinc, and copper), taken by mouth by people at risk of developing advanced AMD, reduced the risk of progression to advanced AMD by 25 percent and the risk of moderate vision loss by 19 percent. People at risk for AMD are advised not to smoke and to maintain a healthy lifestyle, with a diet including leafy green vegetables and fish.”
A total of 1,052 participants over the age of 50 (average age of 71) who had 10 or more large drusen and a visual acuity of 20/40 or better in each eye were enrolled through 22 clinical centers. One eye of each participant was treated and the other eye was observed throughout the five years of the trial. After five years, 20.5 percent of the treated eyes and 20.5 percent of the untreated eyes had lost three or more lines of visual acuity on a standard eye chart. Likewise, 20 percent of treated and untreated eyes progressed to advanced AMD. Change in visual acuity was strongly associated with the development of advanced AMD, but not with treatment group.
“Laser treatment applied to eyes with large drusen that are at high risk for vision loss from AMD had neither a clinically significant beneficial nor harmful effect,” said Stuart L. Fine, M.D., professor of ophthalmology and director of the Scheie Eye Institute at the University of Pennsylvania, and CAPT chairman. “There is no evidence from this trial to suggest that people with large drusen should seek preventive laser treatment.”
The NEI has just launched a nationwide study to see if a modified combination of vitamins, minerals, and fish oil can further slow the progression of vision loss from AMD. This new study, called the Age-Related Eye Disease Study 2 (AREDS2), will build upon results from the earlier AREDS study.