Objective: To evaluate the efficacy and safety of low-intensity laser treatment in the prevention of visual acuity (VA) loss among participants with bilateral large drusen.
Design: Multicenter randomized clinical trial. One eye of each participant was assigned to treatment, and the contralateral eye was assigned to observation.
Participants: A total of 1052 participants who had > or =10 large (>125 microm) drusen and VA> or =20/40 in each eye enrolled through 22 clinical centers.
Intervention: The initial laser treatment protocol specified 60 barely visible burns applied in a grid pattern within an annulus between 1500 and 2500 mum from the foveal center. At 12 months, eyes assigned to treatment that had sufficient drusen remaining were retreated with 30 burns by targeting drusen within an annulus between 1000 and 2000 mum from the foveal center.
Main outcome measure: Proportion of eyes at 5 years with loss of > or =3 lines of VA from baseline. Secondary outcome measures included the development of choroidal neovascularization or geographic atrophy (GA), change in contrast threshold, change in critical print size, and incidence of ocular adverse events.
Results: At 5 years, 188 (20.5%) treated eyes and 188 (20.5%) observed eyes had VA scores > or = 3 lines worse than at the initial visit (P = 1.00). Cumulative 5-year incidence rates for treated and observed eyes were 13.3% and 13.3% (P = 0.95) for choroidal neovascularization and 7.4% and 7.8% (P = 0.64) for GA, respectively. The contrast threshold doubled in 23.9% of treated eyes and in 20.5% of observed eyes (P = 0.40). The critical print size doubled in 29.6% of treated eyes and in 28.4% of observed eyes (P = 0.70). Seven treated eyes and 14 observed eyes had an adverse event of a > or =6-line loss in VA in the absence of late age-related macular degeneration or cataract.
Conclusion: As applied in the Complications of Age-Related Macular Degeneration Prevention Trial, low-intensity laser treatment did not demonstrate a clinically significant benefit for vision in eyes of people with bilateral large drusen.