Effectiveness of laser photocoagulation in clinically significant macular edema with focal versus diffuse parafoveal thickening on optical coherence tomography.

Background And Objective: To evaluate whether increased foveal thickness in clinically significant diabetic macular edema responds differently to modified focal/grid laser photocoagulation in the setting of focal versus diffuse parafoveal thickening as defined by optical coherence tomography (OCT) criteria.

Patients And Methods: The medical records of patients undergoing macular laser procedures for clinically significant diabetic macular edema were retrospectively reviewed. OCT, demographic, and clinical data were recorded for 62 consecutive eyes with clinically significant diabetic macular edema and foveal thickening (> 230 microns). Diffuse parafoveal thickening was defined as having all four parafoveal OCT quadrants greater than 300 microns, whereas focal thickening was defined as having fewer than four quadrants greater than 300 microns.

Results: Mean foveal thickness decreased from 331 to 311 microns with relatively stable visual acuity (20/54 vs 20/51) after a single laser treatment session. The diffuse parafoveal edema subgroup (24 eyes) had a mean foveal thickness change from 383 to 366 microns (P = .47) and mildly decreased visual acuity (20/62 vs 20/69). The focal parafoveal edema subgroup (38 eyes) experienced statistically significant foveal thinning from 299 to 276 microns (P = .018) and mildly improved visual acuity (20/48 to 20/43).

Conclusion: Increased foveal thickening associated with clinically significant diabetic macular edema responds more favorably to modified focal/grid laser photocoagulation in the setting of focal parafoveal edema by OCT criteria. Statistically significant foveal thinning occurred following treatment in the focal group (P = .018) but not the diffuse group (P = .47). Furthermore, eyes with focal parafoveal edema experienced a more beneficial visual acuity response than those with diffuse edema (P = .049).