Optical coherence tomographic patterns in diabetic macular oedema: prediction of visual outcome after focal laser photocoagulation

Aim: To identify optical coherence tomography (OCT) patterns predictive of visual outcome in diabetic macular oedema (DMO) patients who undergo focal laser photocoagulation. Methods: This study involved 70 eyes (45 patients) with clinically significant macular oedema that underwent focal laser photocoagulation using the Early Treatment Diabetic Retinopathy Study protocol. Preoperative macular OCT images were retrospectively examined. OCT features were classified into four patterns: diffuse retinal thickening (DRT); cystoid macular oedema (CMO), serous retinal detachment 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). The 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 CMO or VMIA patterns. Proportions of patients with persistent DMO (central macular thickness >250 mu m after laser treatment) were greater for the CMO and VMIA patterns than DRT pattern. Conclusion: DRT patients achieved a greater reduction in retinal thickening and greater VA increases than CMO and VMIA patients. We suggest that classifying DMO structural patterns using OCT might allow visual outcome to be predicted after laser photocoagulation.