Infrared micropulsed laser treatment for diabetic macular edema – Subthreshold versus threshold lesions

Abstract

Purpose. To assess the effectiveness of subthreshold (invisible after placement) and threshold (barely visible after placement) 810 nm laser photocoagulation in the treatment of clinically significant diabetic macular edema. Methods. A grid of subthreshold laser spots was used to treat patients with diabetic edema. Retrospectively, the results of treatment of 20 eyes of 20 patients were compared to the results of treatment of 120 eyes of 120 patients using a grid of threshold laser lesions. Results. At six months, 60% of subthreshold treated eyes and 75% of threshold treated eyes showed anatomic resolution of macular edema. Improvement or stabilization of visual acuity was achieved in 85% of threshold or subthreshold treated eyes. Conclusion. Gentle grid treatment of regions of diabetic macular edema was effective in ameliorating the edema and limiting visual loss. Subthreshold laser was less effective in promoting resolution of edema compared to threshold lesions, though the difference was not significant in this instance.