Modified grid argon (blue-green) laser photocoagulation for diffuse diabetic macular edema.

One hundred sixty eyes of 92 patients with diffuse diabetic maculopathy with or without cystoid macular edema were enrolled in a prospective randomized clinical trial to determine the efficacy of "modified grid" argon (blue-green) laser photocoagulation. At the 12- and 24-month follow-ups, visual acuity significantly improved in treated eyes (P = 0.00007 and P = 0.00031, respectively) compared to the observation group. In addition, at the 12- and 24-month follow-ups, visual acuity significantly worsened in observation eyes (P = 0.00007 and P = 0.0007, respectively) compared to the treatment group. The following factors did not statistically alter the visual prognosis: a history of systemic hypertension (P = 0.2921); systemic vascular disease (P = 0.5324); cystoid macular edema (P = 0.1010); and initial poor visual acuity (P = 0.3032).