[Characteristics associated with visual improvement after focal photocoagulation in diabetic macular edema]

Photocoagulation reduces the incidence of moderate visual loss in patients with clinically significant macular edema (CSME). However, the incidence of visual improvement after treatment is low. Diffuse retinal thickening identified with optical coherence tomography (OCT) and visual loss before treatment have been associated with visual improvement.

To identify features associated with visual improvement after focal photocoagulation for CSME.

Observational, analytical, longitudinal, retrospective study. Diabetic patients with CSME treated with focal photocoagulation were evaluated. Study variables were: visual improvement (defined as a gain of one or more lines in a vision chart) and ocular and systemic features before treatment. Clinical and ancillary test variables were compared between eyes with and without visual improvement. Mann-Whitney's U was used to compare quantitative variables; χ(2) was used for qualitative variables.

99 eyes of 72 patients mean age 60.6 years, 59.6% females. 38.4% had visual improvement after treatment. The incidence of visual improvement was higher in eyes with vision < 20/40 before treatment (58.8 vs. 16.7%, p < 0.001, relative risk 3.53). In eyes with vision = 20/40 before treatment, the probability of improving was 12 times higher when field 7 of the OCT map had no thickening (p < 0.001). The remaining variables showed no significant associations.

Up to 48% of treated eyes could achieve visual improvement. Consistently with previous reports, the probability increased in eyes with vision < 20/40 before photocoagulation; when vision before treatment was = 20/40, the incidence of visual improvement increased significantly in eyes without thickening in the temporal parafoveal retina.