Segmentational analysis of retinal thickness after vitrectomy in diabetic macular edema

To measure the inner and outer retinal thicknesses on spectral-domain optical coherence tomography (SD-OCT) and evaluate their association with logMAR after vitrectomy for diabetic macular edema (DME). In this retrospective case series, there were 55 consecutive eyes with DME for which vitrectomy was performed. The total retinal thickness, the inner thickness (from the innermost of the retina to the inner nuclear layer), and the outer thickness (from the outer plexiform layer to the retinal pigment epithelium) in the parafoveal subfields were measured manually, and the association with logMAR was evaluated. The total retinal thicknesses in the central, nasal, and inferior subfields were significantly (r = 0.37, P = 0.005; r = 0.29, P = 0.032; r = 0.33, P = 0.015, respectively) associated with the baseline logMAR; no subfield thickness was correlated with the logMAR at the final visit. However, segmentational analysis showed that the outer retinal thickness of the temporal subfield was associated with disruption of the junction between the inner and outer segments at the fovea (P = 0.021 and P = 0.005) and negatively correlated with the logMAR (r = -0.37, P = 0.006 and r = -0.28, P = 0.042) at the 6-month and final visit. The inner thickness of the nasal subfield did not change after vitrectomy compared with the other subfields and the outer thickness of all subfields in the parafoveal area; the baseline nasal total thickness was correlated most significantly with the logMAR (r = 0.40, P = 0.002 and r = 0.37, P = 0.006) at the 6-month and final visits. Segmentational analysis provided useful information for considering the prognosis and pathogenesis after vitrectomy for DME.