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BACKGROUND AND OBJECTIVE To determine the prophylactic and therapeutic value of a single subthreshold 810-nanometer laser treatment in patients with high risk drusen as a manifestation of dry age-related macular degeneration in both eyes. PATIENTS AND METHODS The Prophylactic Treatment of Age-related Macular Degeneration study enrolled 1,278 eyes of 639 participants who were 50 years or older with at least 5 drusen 63 µm or more in diameter in each eye. Treatment consisted of the placement of an annular grid of 48 extrafoveal, subthreshold 810-nm diode laser applications centered at but sparing the foveola in one eye of each participant, with the fellow eye serving as a control. Development of choroidal neovascularization and change in best-corrected visual acuity were compared between treated and untreated eyes. RESULTS Subthreshold laser treatment did not decrease the incidence of choroidal neovascularization in treated versus untreated eyes. A modest visual acuity benefit in treated eyes was found at 24 months (1.5 letter difference; P = .04) and in the treated eyes of participants with a baseline visual acuity between 20/32 and 20/63 (4.0 letter difference; P = .0034). However, this treatment effect was not sustained at 3 years. CONCLUSION A single subthreshold 810-nanometer laser treatment to eyes of participants with bilateral high risk drusen is not an effective prophylactic strategy against choroidal neovascularization. [Ophthalmic Surg Lasers Imaging 2009;40:530-538.] AUTHORS From the UPMC Eye Center (TRF, PMB), University of Pittsburgh, Pittsburgh, Pennsylvania; the Shiley Eye Center (WRF), University of California–San Diego, La Jolla, California; and the W. K. Kellogg Eye Center (DCM), University of Michigan, Ann Arbor, Michigan. Accepted for publication December 19, 2008. Supported by Iridex Corporation, Mountain View, California, and the sources listed under the individual center descriptions found at the end of the article; the Eye and Ear Foundation of Pittsburgh, Pittsburgh, Pennsylvania; Research to Prevent Blindness, Inc., New York, New York; and unrestricted funds from several participating centers. Presented in part at the annual meeting of the American Academy of Ophthalmology, October 15-18, 2005, Chicago, Illinois, and the annual meeting of the Association for Research in Vision and Ophthalmology, April 30-May 4, 2006, Ft. Lauderdale, Florida. The authors thank photographic readers Cheryl Hiner, Columbia, MD, Rosemary J. Brothers, Madison, WI, and Linda Huang, MD, and Maria Palaiou, MS, Pittsburgh, PA; the Data and Safety Monitoring Committee voting members Donald J. D’Amico, MD, Mark W. Johnson, MD, J. Richard Landis, PhD, and nonvoting ex-officio member, Dr. Musch; and Giorgio Dorin for his contribution to the manuscript. The authors have no financial or proprietary interest in the materials presented herein. Address correspondence to Thomas R. Friberg, MS, MD, UPMC Eye Center, 203 Lothrop Street, Suite 824, Pittsburgh, PA 15213. doi: 10.3928/15428877-20091030-01

PURPOSE: To determine the predictors of drusen reduction in eyes with nonexudative age-related macular degeneration (ARMD) treated with subthreshold infrared (810 nm) diode laser macular grid photocoagulation. Additionally, to determine the relationship of laser-induced drusen reduction and best-corrected visual acuity (BCVA) 18 months after laser treatment. DESIGN: Randomized controlled clinical trial. METHODS: Fifty patients (100 eyes) with bilateral nonexudative ARMD were enrolled at two centers. One eye of each patient was randomized to the observation; the other eye was treated with 48 subthreshold (invisible end point) applications of infrared (810 nm) diode laser in a macular grid pattern. The eyes that received subthreshold laser treatment were compared with the eyes that received no treatment. The baseline fundus characteristics (number, size, and distribution of drusen, as well as focal hyperpigmentation) from two macula areas (central 1500 μ diameter, pericentral 1500 μ ring area) on stereo color photographs, the number of laser-induced lesions, and the area of laser induced retinal pigment epithelial (RPE) lesions on fluorescein angiography 3 months after treatment were studied as predictors of major drusen reduction (≥ 50% drusen reduction from baseline) 18 months after laser treatment. BCVA at baseline and 18 months later was compared in observation eyes and in laser-treated eyes. RESULTS: Eighteen months after randomization, 24 (48%) of 50 eyes treated with subthreshold laser had major drusen reduction compared with three (6%) of 50 observation eyes ( P = .00001). At 3 months post-treatment in laser-treated eyes with major drusen reduction, the mean number of laser-induced lesions on fluorescein angiography was 30.7 and the mean area of RPE change was 0.81 mm 2 compared with 14.8 laser-induced lesions and 0.35 mm 2 area of RPE change in eyes without major drusen reduction ( P = .0001 and P = .0003, respectively). At baseline, fundus characteristics were not significantly different between observation eyes and laser-treated eyes or between the major drusen reduction group and the nonmajor drusen reduction group. At 18 months after treatment, BCVA was not significantly different in laser-treated eyes and in observation eyes. CONCLUSIONS: Subthreshold infrared (810 nm) diode laser macular grid photocoagulation in eyes with nonexudative ARMD significantly reduced drusen 18 months after laser treatment. Both the number of subthreshold laser lesions and the area of RPE changes visible on fluorescein angiography 3 months after treatment appeared to be predictors for major drusen reduction 18 months after treatment. However, it remains to be determined whether laser-induced drusen reduction is beneficial for visual acuity or reduces the incidence of choroidal neovascularization (CNV) in eyes with nonexudative ARMD.