Validation of Deep Capillary Plexus OCTA Metrics as Predictors of Diabetic Retinopathy Complications: A One-Year Longitudinal Study

Diabetic retinopathy (DR) can lead to vision-threatening complications, and tools that capture microvascular damage beyond standard clinical grading of disease severity may improve risk prediction. Optical coherence tomography angiography (OCTA) quantifies retinal perfusion, but its prognostic value in referable DR is not fully established. We aimed to validate baseline deep capillary plexus (DCP) OCTA metrics for predicting one-year complications in eyes with referable DR. In this prospective longitudinal study in 137 eyes of 96 participants, we assessed baseline predictors of DR complications, defined as best-corrected visual acuity (BCVA) loss (≥ 10 letters on the ETDRS chart), center-involving diabetic macular edema, anti-VEGF injections, pan-retinal photocoagulation, or vitreous hemorrhage. Baseline variables included BCVA, low-luminance visual acuity (LLVA), ocular parameters, demographic characteristics, systemic variables, and OCTA metrics (foveal avascular zone area, vessel density [VD] and geometric perfusion deficit in the superficial capillary plexuses [SCP] and [DCP]). Logistic regression prioritized variables with pathophysiologic relevance while minimizing risk of collinearity. Receiver operating characteristic (ROC) curves assessed whether DCP OCTA metrics improved discrimination beyond a clinical model with traditional risk factors. Over one year, 34 eyes (24.8%) experienced one or more complications. Multivariate analysis including DR severity, DCP VD, and LLVA identified higher baseline DR severity (OR, 5.77; 95% CI: 1.93 to 17.27; P = 0.002) and lower DCP VD (OR, 0.59; 95% CI: 0.36 to 0.95; P = 0.031) as significant predictors. Adding DCP VD to the clinical model significantly improved discrimination. These findings support DCP OCTA metrics as capillary-level biomarkers for risk stratification in referable DR and highlight the need for larger longitudinal studies to confirm clinical utility.