Association between retinal layer thickness and perfusion status in extramacular areas in diabetic retinopathy.

PURPOSE: This study was performed to investigate the association between changes in retinal layer thickness and perfusion status in the extramacular areas of eyes with diabetic retinopathy. DESIGN: Retrospective cross-sectional study. METHODS: The medical records of 70 eyes from 55 patients with diabetes were reviewed. The status of retinal perfusion in extramacular areas was evaluated using swept-source optical coherence tomography (SS-OCT) angiography. Retinal layer thickness was measured in nonperfused areas (NPA) larger than two optic disc area, areas of sparse capillaries (SC), and perfused areas (PA-DR) in eyes with diabetic retinopathy. Retinal layer thickness was also measured in perfused areas in eyes without diabetic retinopathy (PA-NDR), and the thicknesses were then compared. In addition, SS-OCT angiography images and retinal thickness maps were compared to investigate the distribution of retinal thickness changes and spatial relationships to areas of retinal perfusion. RESULTS: The inner retinal thickness in NPA was significantly thinner than the inner retinal thicknesses in SC, PA-DR and PA-NDR (all P<0.001), and the inner retinal thickness in PA-NDR and SC was significantly thinner than that in PA-DR (P=0.006 and 0.031, respectively). In a distribution analysis of the extramacular areas, NPA spatially overlapped with areas of severe retinal thinning in all locations. Local thickening with smooth shapes and gentle borders overlapped with areas of capillary abnormalities. Neovascularization was present at sites of local thickening with irregular shapes and unnatural clear borders. CONCLUSIONS: Changes in retinal layer thickness were associated with perfusion status, suggesting that retinal thickness maps can reflect perfusion status.