Therapeutic benefits of infrared (810-nm) diode laser macular grid photocoagulation in prophylactic treatment of nonexudative age-related macular degeneration - Two-year results of a randomized pilot study

Objective: This pilot study collected preliminary information on the effect iveness and safety of infrared (810-nm) diode laser macular grid photocoagu lation in patients with nonexudative age-related macular degeneration (AMD) . Results from this pilot study were used in designing a larger, multicente r, randomized clinical trial. Design: A multicenter, randomized, controlled, clinical trial. Participants: A total of 229 eyes of 152 patients with AMD were enrolled in the pilot study. Seventy-five patients with 1 eye eligible (75 eyes) were enrolled in the unilateral arm of the study; 77 patients with both eyes eli gible (154 eyes) were enrolled in the bilateral arm of the study. In the un ilateral study arm, 32 eyes were randomized to the observation group, 27 ey es were treated with visible endpoint burns, and 16 eyes were treated with invisible endpoint (subthreshold) lesions. In the bilateral study arm, 77 e yes were in the observation group, 36 eyes were treated with visible burns, and 41 eyes were treated with subthreshold (invisible) lesions. Intervention: Eyes were treated with infrared (810-nm) diode laser macular grid photocoagulation using either visible burns or subthreshold (invisible ) lesions and compared to eyes receiving no treatment. Main Outcome Measures: Reduction of drusen, change in visual acuity, and ra te of choroidal neovascularization (CNV) membrane formation. Results: At 12 months after treatment, 62% of eyes treated with visible bur ns had a clinically significant reduction in drusen, whereas this proportio n (65%) was reached in 18 months for eyes treated with subthreshold lesions . At 24 months' follow-up, treated eyes had a significant reduction in drus en compared to observation eyes (P < 0.0001). Visual acuity was significant ly improved in treated eyes at 12, 18, and 24 months compared to observatio n eyes (P < 0.001). Choroidal neovascularization formation was similar in t reated and observation eyes through 24 months' follow-up. Complications inc luded CNV associated with six eyes treated with visible burns and a juxtafo veal laser scar in one eye treated with visible burns. Conclusions: Infrared (810-nm) diode laser macular grid photocoagulation in patients with nonexudative AMD significantly reduces drusen levels (P < 0. 0001) and significantly improves visual acuity (P < 0.001) when either visi ble endpoint burns or subthreshold endpoint lesions are used. Complications were fewer using subthreshold endpoint lesions. A larger, multicenter, pro spective clinical trial with longer follow-up is needed to determine the ef ficacy of treatment in reducing the rate of CNV formation. Data from this c linical pilot study have been used to design the Prophylactic Treatment of AMD Trial (PTAMD), a multicenter, randomized, prospective clinical trial cu rrently in progress comparing subthreshold (invisible) treatment to observa tion in eyes with nonexudative AMD.