Aim: To identify optical coherence tomography (OCT) patterns predictive of visual outcome in diabetic macular edema (DME) patients who undergo focal laser photocoagulation.
Methods: This study involved 70 eyes (45 patients) with clinically significant macular edema that underwent focal laser photocoagulation using the Early Treatment Diabetic Retinopathy Study protocol. Two independent masked observers retrospectively examined preoperative macular OCT images. OCT features were classified into four patterns: diffuse retinal thickening (DRT); cystoid macular edema (CME); serous retinal detachment (SRD); and vitreomacular interface abnormalities (VMIA). Changes in retinal thickness, retinal volume, and visual acuity (VA) after focal laser photocoagulation were evaluated and compared with respect to their OCT features.
Results: After focal laser photocoagulation, changes in retinal thickness and retinal volume were significantly different for different OCT types (P=0.002 and P<0.001). Change in VA from baseline was not significantly different between groups (P=0.613). The DRT pattern was associated with a greater reduction in retinal thickening and better VA improvement than the CME or VMIA patterns. Proportions of patients with persistent DME (central macular thickness > 250 μm after laser treatment) were greater for the CME and VMIA patterns than DRT pattern.
Conclusion: DRT patients achieved a greater reduction in retinal thickening and greater VA increases than CME and VMIA patients. We suggest that classifying DME structural patterns using OCT might allow visual outcome to be predicted after laser photocoagulation.