Effect of photocoagulation on center point thickness in diabetic macular edema.

Background: Photocoagulation is the standard treatment for clinically significant macular edema (CSME). This procedure is effective in reducing macular thickening, but it has been reported that initially it does not improve the thickness at the area of best visual function (center point of the fovea). We undertook this study to compare the effect of focal photocoagulation on center point thickness (CPT) and macular volume 3 weeks after treatment in Mexican diabetic patients with CSME, with and without center point involvement.

Methods: We carried out an observational, retrospective, longitudinal, analytical, open study. Type 2 diabetic patients undergoing focal photocoagulation for CSME at a general hospital in Mexico City were evaluated. Mean CPT and macular volume were compared before and 3 weeks after photocoagulation (paired t test) in the sample and in eyes with (group 1) and without (group 2) baseline center point involvement. Absolute and percent CPT and macular volume changes were identified.

Results: Fifty-nine eyes (mean age 59.6 years) were studied. CPT mean increased from 193 to 197 μm (p = 0.3), statistically in group 2 (168.8 to 178.5 μm, p <0.001). Macular volume mean changed from 7.8 to 7.6 mm(3) (p <0.001). CPT increased 3.9 μm (3%) in the sample, whereas macular volume decreased 0.26 mm(3) (3.1%). Correlation between changes was 0.089.

Conclusions: Although macular volume decreased statistically 3 weeks after photocoagulation, CPT did not and increased statistically in eyes without baseline center point involvement, which was unnoticed in the sample effect. These changes should not be overlooked because dealing with them could improve the early results of treatment.