Qualitative and Quantitative Assessment of Restored Capillary Perfusion on OCT Angiography in Diabetic Macular Ischemia

Purpose: The purpose of this study was to investigate characteristics of restored capillary perfusion on optical coherence tomography angiography (OCTA) in diabetic retinopathy (DR). Methods: We prospectively obtained OCTA images from 106 eyes of 106 patients with DR and analyzed them within a 2.5-mm-diameter circle. The area was divided into 15 × 15-pixel squares; those without vascular edge signals were defined as nonperfusion squares (NPSs) at baseline and 3 years after image registration. Qualitative assessment identified OCTA findings representing restored perfusion: newly developed uniform-caliber vessels ("rod-like vessels"), vessels with distal enlargement ("bulb sign"), loop-forming vessels ("loop vessel"), and "vessel reappearance" suggestive of reperfusion. Results: In the superficial layer, eyes with advanced diabetic macular ischemia (DMI) showed NPS reduction in the central subfield more frequently than those with mild DMI (P < 0.001). Baseline NPS counts were negatively correlated with 3-year NPS changes in the central sector of the superficial and deep layers (P < 0.05). In the deep layer, NPS reduction in the parafoveal sectors was observed more frequently in eyes with advanced DMI (P < 0.05). Qualitative assessment showed rod-like vessels, bulb signs, loop vessels, and vessel reappearance in 81, 75, 11, and 93 eyes, respectively. Rod-like vessels and bulb signs were more frequently observed outside the foveal avascular zone (FAZ) than within it in the superficial layer (P < 0.001 for both comparisons). Conclusions: Quantitative and qualitative analyses demonstrated restored capillary perfusion on OCTA in some eyes with DMI, suggesting revascularization and reperfusion. Translational Relevance: Advanced DMI exhibits both progressive capillary nonperfusion and restored capillary perfusion on OCTA.