Clinical characterization of 3-year progression of diabetic macular ischemia on OCT angiography.

To characterize the progression of capillary nonperfusion in diabetic macular ischemia (DMI) using optical coherence tomography angiography (OCTA) images. A single-center, prospective case series study. We acquired 3 × 3 mm swept-source OCTA images and created en face images within a central 2.5 mm circle in 100 eyes of 100 patients with diabetic retinopathy (DR). The circle was divided into 15 × 15-pixel squares; squares without retinal vessels were defined as nonperfusion squares (NPSs). Vessel density (VD) and vessel length density (VLD) were also quantified as perfusion metrics. We compared these metrics at baseline and at the 3-year follow-up visit. Both VD and VLD decreased, and NPS increased at 3 years in both superficial and deep layers. The baseline superficial and deep non profusion squares' (NPS) counts correlated with the count at 3 years but not with its changes. Multivariate analyses demonstrated that logMAR (β = 0.785, P < 0.001) and PDR (β = 0.206, P = 0.002) at baseline predicted poorer VA at 3 years. PDR (β = 0.275, P = 0.007) and NPS counts in the inferior sector of the superficial layer (β = -0.223, P = 0.027) at baseline were mildly associated with VA deterioration. Age was the only baseline parameter correlated with changes in superficial NPS counts (β = 0.242, P = 0.015). Changes in deep NPS counts were associated with systemic hypertension (β = -0.262, P = 0.005), logMAR (β = 0.307, P = 0.001), and prior vitrectomy (β = -0.209, P = 0.024). We demonstrated changes in the nonperfusion metrics on OCTA images over 3 years and identified baseline factors associated with the progression of nonperfusion areas.