The Course of Response to Focal/grid Photocoagulation for Diabetic Macular Edema

Abstract

Purpose: To determine whether eyes with center involved diabetic macular edema (DME), treated with focal/grid photocoagulation, in which there is a reduction in central subfield thickness (CST) measured with optical coherence tomography (OCT) after 16 weeks, will continue to improve if retreatment is deferred. Methods: Prospective, multi-center, observational, single group focal/grid photocoagulation study of 122 eyes with center involved DME (OCT CST ≥250μ). At the 16-week visit and continuing every 8 weeks, eyes were assessed for retreatment and additional laser was deferred if the visual acuity letter score improved ≥5 letters or OCT CST decreased ≥10% compared with the visit 16 weeks prior. Results: Of the 115 eyes that completed the 16-week visit, 54 (47%) had a decrease in CST by ≥10% compared with baseline. Of these, 26 (48%) had a CST ≥250μ at 16 weeks and were evaluable at 32 weeks. Eleven (42%, 95% confidence interval 23% to 63%) of the 26 eyes had a further decrease in CST ≥10% from 16 to 32 weeks without further treatment. Conclusion: Sixteen weeks following focal/grid laser for DME, in eyes with a definite reduction, but not resolution, of central edema, 23% to 63% will continue to improve without additional treatment.