Diagnostic potential of OCTA for early detection of diabetic retinopathy: A literature review

Abstract

Background Early detection of diabetic retinopathy (DR) is crucial for preventing blindness. Optical coherence tomography angiography (OCTA) offers a non-invasive method for visualizing retinal microvasculature and may facilitate earlier detection of DR. This systematic review evaluates the current evidence regarding OCTA-derived biomarkers for the identification of early DR. Methods A systematic review of the literature was performed. Due to substantial heterogeneity in study designs, OCTA protocols, and outcome measures, a meta-analysis was not feasible. Results Twenty-one studies were included. OCTA scan sizes ranged from 3 × 3 mm to 6 × 6 mm and evaluated both the superficial and deep capillary plexuses. Vessel density (VD) was the most consistently reported biomarker, with reduced VD observed in early DR in 13 of 15 studies. Enlargement of the foveal avascular zone (FAZ) was reported in 9 of 17 studies. Microaneurysms were more frequently identified in diabetic eyes in 3 of 5 studies, while increased vessel tortuosity was reported in 2 of 5 studies. Discussion Current evidence suggests that OCTA can detect retinal microvascular abnormalities associated with early DR before advanced clinical manifestations become evident. Reduced VD emerged as the most consistent indicator of early disease, while an increased microaneurysm burden may serve as a complementary marker. In contrast, the diagnostic value of FAZ alterations remains uncertain. Conclusion By identifying the OCTA parameters most strongly associated with early DR, this review suggests the potential role of OCTA in earlier diagnosis, risk stratification, and monitoring of diabetic patients.