Analysis of Vessel Density and Foveal Avascular Zone in Proliferative Diabetic Retinopathy based on Internal Carotid Artery Stenosis Grade Using OCTA

Purpose: This study investigates the relationship between retinal changes in proliferative diabetic retinopathy (PDR) patients and the severity of internal carotid artery (ICA) stenosis, using optical coherence tomography angiography (OCTA). The goal is to explore potential correlations between ICA stenosis and specific retinal parameters, aiding in risk factor identification. Methods: A retrospective analysis was conducted on 73 PDR patients (146 eyes), assessing carotid artery stenosis (CAS) severity via neck CT angiography and carotid doppler ultrasonography. Patients were divided into two groups based on ICA stenosis: normal to mild (Group I) and moderate or above (Group II). Retinal parameters, including the foveal avascular zone (FAZ) area and vessel density in both superficial and deep capillary plexuses, were analyzed using OCTA and Image J software. Statistical adjustments were made for age differences between the groups, and appropriate statistical methods were employed to account for the non-independence of eyes within the same patient and small sample size in Group II. Results: The average age was 64.84±9.4 years. Group II patients were on average about 5 years older than Group I, and this age difference was significant. After adjusting for age, significant differences remained between the groups in macular vessel density of the superficial plexus and FAZ area, with Group II showing decreased vessel density and increased FAZ area in severe ICA stenosis cases. However, deep capillary plexus vessel density showed no significant variation. Conclusions: OCTA demonstrates that increased ICA stenosis in PDR patients correlates with decreased macular vessel density and expanded FAZ area, underscoring the need for carotid assessments. Early microvascular changes detectable by OCTA, even at mild NPDR stages, may indicate disease progression, positioning OCTA as a crucial non-invasive monitoring tool.