LONGITUDINAL QUANTITATIVE EVALUATION OF RETINAL AND CHOROIDAL VASCULATURE IN DIABETIC PATIENTS WITH AND WITHOUT RETINOPATHY USING OCT, OCTA, AND SEMI-AUTOMATED MATLAB METHOD

PURPOSE: To evaluate longitudinal retinal and choroidal vascular changes in diabetic patients with and without diabetic retinopathy (DR) using OCT, OCTA, and MATLAB analysis, and to identify quantitative biomarkers of stage and progression. METHODS: In this prospective study, 142 diabetic eyes (Stage 0-3 DR) and 34 controls were followed for 2 years. Eyes with diabetic macular edema were excluded. Participants underwent SD-OCT, macular 6 × 6-mm OCTA, and wide-field FA at baseline, 8, 16, and 24 months. Parameters included retinal thickness, subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI), choriocapillaris flow, vessel density (VD), skeleton density (SD), fractal dimension (FD), vessel diameter index (VDI), vessel tortuosity (VT), foveal avascular zone (FAZ), and acircularity index (AI), quantified with MATLAB. RESULTS: At baseline, diabetic eyes had lower SFCT and CVI versus controls ( P = 0.004, P = 0.035). Stage 0 eyes already showed impairment, with reduced VD, SD, and FD, and increased VDI and AI. Over 2 years, DR eyes exhibited declines in SFCT, CVI, and superficial VD, with rising VDI and AI. ROC analysis showed deep VDI best distinguished Stage 0 from Stage 1 (AUC = 0.764), superficial VDI separated Stage 2 from Stage 3 (AUC = 0.720), whereas deep VD and ischemic index (ISI) distinguished Stage 0 from Stages 1 to 3 (AUC > 0.80). CONCLUSION: DR is associated with retinal and choroidal vascular alterations detectable by OCT and OCTA. Quantitative metrics-particularly deep VDI and CVI-are promising biomarkers for early detection, staging, and monitoring of DR.