Photocoagulation for clinically significant macular edema is effective to reduce the incidence of moderate visual loss. Selective photocoagulation for focal macular edema statistically reduces macular thickening, measured with optical coherence tomography, as early as two weeks after treatment, without significant changes over center point thickness. Although anatomic improvement has been demonstrated with OCT, clinical improvement takes longer to be evident: the Early Treatment Diabetic Retinopathy Study describe that clinical differences in visual function are after the eight month, and all the treatment strategies for macular edema used in this study were associated with an increased rate of moderate visual loss, during the first six weeks. Differences in research can achieve statistical significance, without clinical significance. A study was conducted to identify changes of visual function three weeks after photocoagulation for focal macular edema, and to correlate them with changes of CPT and macular volume, in order to compare the behavior of anatomical changes with visual changes.