Therapeutic effect of macular grid photocoagulation in treatment of nonexudative age-related macular degeneration.

Background: To investigate the effect of prophylactic subthreshold laser macular grid photocoagulation on drusen area and to evaluate the visual outcome and incidence of choroidal neovascularization in patients with soft drusen maculopathy.

Methods: In a nonrandomized nonmasked clinical trial, 18 patients (36 eyes) with bilateral soft drusen maculopathy were studied. For each patient, one eye was treated with 48 subthreshold (invisible end-point) applications of 532-nm KTP-laser in a macular grid pattern and the fellow eye was observed. Soft drusen areas were calculated and compared between the two groups at baseline and follow-up visits at 3, 6, 12, and 30 months of therapy. Best corrected visual acuity was also compared in observed and laser-treated eyes. Reduction of drusen area, change in visual acuity, and rate of CNV were assessed in both groups.

Results: At baseline, there was no significant difference in the mean drusen surface area between the two groups (P = 0.90). The mean surface area of soft drusen in treated eyes was 6.51 mm(2) after 30 months and 7.58 mm(2) (P = 0.50) in the control eyes. There was a trend towards reduction in the mean soft drusen area after 30 months from baseline in laser-treated eyes (6.51 vs. 6.97 mm(2)). In treated eyes, there was no statistically significant difference between the mean best corrected visual acuity at the baseline (0.28 logMAR) and after 30 months (0.32 logMAR) (P = 0.40).

Conclusion: Subthreshold macular grid photocoagulation with 532-nm KTP-laser did not seem to reduce drusen surface area significantly and did not improve best corrected visual acuity after 30 months. No exudative lesion developed in laser-treated eyes.