Abstract
By utilizing widefield swept-source optical coherence tomography angiography (WSS-OCTA) to quantify choroidal vascular density (VD) in order to identify early fundus changes in diabetic patients and to predict the progression of diabetic retinopathy (DR). A total of 101 eyes, including patients with type 2 diabetes mellitus and controls, were included in the cross-sectional study. Diabetic patients were stratified into three groups based on disease severity: non-DR (NDR), nonproliferative DR (NPDR), and proliferative DR (PDR). Fundus images obtained through WSS-OCTA were segmented into nine 2 mm × 2 mm regions centered on the macula: supratemporal (ST), superior (S), supranasal (SN), temporal (T), central macular area (C), nasal (N), inferotemporal (IT), inferior (I), and inferonasal (IN). Changes in choroidal VD in the choriocapillaris (CC) and mid-large choroidal vasculature (MLCV) layers were evaluated in each region among patients with DR. Additionally, the diagnostic value of choroidal VD in distinguishing different stages of DR was assessed using the area under the receiver operating characteristic (ROC) curve. In comparison to the NDR group, the VD of MLCV (S) was found to decrease significantly in the NPDR group. Furthermore, the VD of CC (S) was significantly lower in the PDR group compared to the NPDR group. The VD of MLCV (IN) demonstrated potential in distinguishing between healthy eyes and those with NDR. Additionally, the VD of CC (SN) and MLCV (S, SN, C, I) showed relatively high area under the curve (AUC) values in discriminating between NDR and NPDR. Lastly, the VD of CC (S) exhibited good diagnostic accuracy in distinguishing between NPDR and PDR patients. As DR advances, MLCV and CC are sequentially compromised to varying degrees. In clinical diagnosis, the VD of the IN region in the MLCV layer serves as a more sensitive early imaging biomarker for detecting preclinical DR, while a decrease in the VD of the S region in the CC layer indicates the onset of PDR.