The course of response to focal/grid photocoagulation for diabetic macular edema.

PURPOSE The purpose of this study was to determine whether eyes with center-involved diabetic macular edema, treated with focal/grid photocoagulation, in which there is a reduction in central subfield thickness (CST) measured with optical coherence tomography after 16 weeks, will continue to improve if retreatment is deferred. METHODS This is a prospective, multicenter, observational, single-group focal/grid photocoagulation study of 122 eyes with center-involved diabetic macular edema (optical coherence tomography CST > or =250 microm). At the 16-week visit and continuing every 8 weeks, eyes were assessed for retreatment and additional laser treatment was deferred if the visual acuity letter score improved > or =5 letters or optical coherence tomography CST decreased > or =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 > or =10% compared with baseline. Of these, 26 (48%) had a CST > or =250 microm at 16 weeks and were evaluable at 32 weeks. Eleven (42%; 95% confidence interval, 23-63%) of the 26 eyes had a further decrease in CST > or =10% from 16 weeks to 32 weeks without further treatment. CONCLUSION Sixteen weeks after focal/grid laser for diabetic macular edema in eyes with a definite reduction, but not resolution, of central edema, 23% to 63% likely will continue to improve without additional treatment.