Retinal Sensitivity and Structural Changes after Focal Photocoagulation for Diabetic Macular Edema: A Multisectorial Comparison

Introduction: The hindrance of a macular laser treatment for diabetic macular edema (DME) remains unclear. Our purpose was to evaluate macular functional and structural changes after focal macular photocoagulation for DME.

Methods: This is a prospective cohort study that included patients with mild diabetic retinopathy, submitted to focal macular laser treatment as monotherapy for DME. Patients underwent optical coherence tomography and microperimetry after the necessary number of treatment sessions for complete resolution of DME. Eyes were compared in each macular sector (superior, temporal, and inferior 1- to 3-mm parafoveal ring) according to the presence of laser spots. Relative sensitivity was calculated as sectorial sensitivity divided by general sensitivity.

Results: Sixty-four eyes were included. In sectors submitted to focal photocoagulation, we observed a significant reduction in absolute sensitivity (-1.0 to -0.4 dB, depending on the sector analyzed) and relative sensitivity (-2.1 to -0.6%) together with a reduction in the outer nuclear layer (ONL) thickness (-8 to -3 μm). The number of laser spots correlated with both functional and structural changes.

Conclusion: In macular sectors that underwent photocoagulation, we found a small reduction in retinal sensitivity together with a reduction in the corresponding ONL thickness.