The advanced stages of AMD destroy the macula in the eye’s retina, the area that normally provides the detailed, central vision we rely on for reading, driving and other daily tasks. This clinical trial, sponsored by the National Eye Institute, did not show that the laser treatment was effective in preventing loss of vision, but the results did provide valuable information on factors that predict progression to advanced AMD.

Patients with early AMD whose eyes have many large drusen---abnormal, white-yellow deposits that accumulate under the retina---are known to be at higher risk for developing one or both forms of advanced AMD: choroidal neovascularization (CNV), known as “wet” AMD, and/or geographic atrophy (GA), known as advanced “dry” AMD. CAPT is the first study large enough to look separately at risk factors for the development of CNV and of advanced GA in AMD patients with extensive drusen in both eyes. The 1,052 CAPT participants each had 10 or more large drusen and visual acuity of 20/40 or better in each eye at the study outset. Each patient received low-intensity laser treatment in one eye only; the other eye was observed. Follow-up exams took place yearly for five or six years. CAPT concluded that laser treatment did not change the risk of developing CNV, GA, or loss of visual acuity.

Analysis of the CAPT results allowed researchers to identify factors that predicted the risk of progression from early to advanced AMD. They found that some factors were associated with both forms of advanced AMD and others with only one form. Increased age and pigment clumps in the retina were associated with the development of both CNV and GA . Current, but not past, smoking was linked to a higher risk of CNV, indicating that smoking is likely an active stimulus to CNV. The size of the retinal area covered by drusen and the presence of lightly pigmented areas in the retina were associated only with progression to GA. “These findings increase the understanding of how CNV and GA develop and aid ophthalmologists in discussing prognosis with patients who have many large drusen,” said Maureen G. Maguire, Ph.D., Professor of Ophthalmology, University of Pennsylvania Health System, and, corresponding author on the risk factors study.-American Academy of Ophthalmology