Region-Specific Choroidal Vascular Alterations in Diabetes Revealed by Ultra-Wide-Field Swept-Source OCTA

• Ultra-wide-field swept-source OCTA (24 × 20 mm) enables comprehensive assessment of choroidal vascular alterations beyond the macula in diabetic eyes. • The nasal-superior region showed the most prominent decreases in CVI, CVV/a, and CSV/a, suggesting regional variability of the choroid in early diabetes. • Nasal-superior CVI and CVV/a demonstrated good diagnostic performance in distinguishing diabetic from non-diabetic eyes, indicating potential non-invasive biomarkers for early diabetic choroidopathy. To compare choroidal vascular alterations using ultra-wide-field swept-source optical coherence tomography angiography (UWF-SS-OCTA) between diabetic eyes and control eyes, and to evaluate their associated factors and diagnostic relevance. UWF-SS-OCTA (24 × 20 mm) was performed in non-diabetic controls (NDM), diabetic patients without retinopathy (NDR), and patients with non-proliferative diabetic retinopathy (NPDR). The scan area was divided into nine regions. Choroidal vascularity index (CVI), choroidal vascular volume per unit area (CVV/a), choroidal stromal volume per unit area (CSV/a), and choroidal stromal index (CSI) were compared among groups. Associations with clinical variables were analysed, and diagnostic performance was assessed using receiver operating characteristic analysis. Mean CVI was significantly reduced in diabetic eyes, including NDR, compared with controls. The nasal-superior region showed the most pronounced reductions in CVI, CVV/a, and CSV/a. These parameters were negatively associated with age and independently influenced by diabetic status. CVI and CVV/a demonstrated good discrimination between diabetic and non-diabetic eyes but did not distinguish NDR from NPDR. Region-specific choroidal vascular impairment occurs early in diabetes. Nasal-superior CVI and CVV/a may serve as non-invasive biomarkers of early diabetic choroidopathy.