Abstract
Abstract: :
Purpose: To determine the predictors of choroidal neovascularization (CNV) in unilateral arm eyes treated with subthreshold diode laser photocoagulation in the Prophylactic Treatment of Age-Related Macular Degeneration (PTAMD) study. Methods: 242 patients were enrolled in the unilateral arm of the PTAMD study. 118 eyes were randomized to the observation group, and 124 eyes were treated with subthreshold diode laser photocoagulation. During follow-up as of 8/31/01, 26 eyes of the treated group developed CNV, versus 17 CNV events in observed eyes (P=0.02, Wilcoxon test of Kaplan-Meier curves). Preoperative stereo fundus photographs and 3 month post treatment angiograms were analyzed in a masked manner for a sample of the treated eyes that developed CNV and of the treated eyes that did not developed CNV. By using computer-assisted analysis, the surface area of drusen was determined at baseline and the 3-month post treatment angiograms were analyzed for number of laser uptake spots. Results: The mean surface area of drusen in treated eyes that subsequently developed CNV was 7.18 4.27 mm2 versus 3.83 1.92 mm2 in eyes that did not develop CNV (P=0.016). There was no association between the number of laser uptake lesions detectable on fluorescein angiogram and the development of CNV (Mean number of laser spots was 27 4 spots in the CNV group versus 30 9 spots in the non CNV group (P=0.56)). Conclusion: This case-control sub-analysis indicates that CNV incidence after prophylactic laser photocoagulation is more likely in eyes with a greater area of drusen preoperatively. The amount of laser induced RPE changes does not predict CNV although our prior work showed that it can predict drusen reduction in bilateral arm patients.
Keywords: 308 age-related macular degeneration • 357 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • 346 choroid: neovascularization