Choroidal vascularity index as a predictor for the development of retinopathy in diabetic patients

Today, limited and controversial data are available on predictive markers for diabetic retinopathy. Choroidal thickness (CT) is an unstable parameter affected by many factors. Also, previous studies had conflicting findings on choroidal thickness. In this study, we aimed to investigate the role of choroidal vascularity index (CVI), a relatively new marker, in evaluating choroidal vascular status and its relationship with diabetic retinopathy (DR).

A total of 124 subjects, 84 patients with type 2 diabetes mellitus (DM) and 40 healthy controls, were included in the study. The patients were divided into two groups as follows: those without DR and those with non-proliferative DR (NPDRP). All subjects underwent enhanced-depth imaging optical coherence tomography (EDI-OCT), and CT values were noted. To measure CVI, luminal (LA) and stromal areas of the choroidal images were binarized using Image J program. CVI was defined as the proportion of LA to total choroid area (TCA). Demographic and laboratory data of the patients were collected retrospectively.

CVI were found to be lower in diabetic patients compared to non-diabetic patients. CVI values in 3 groups were as follows: 67.9% ± 1.8 (healthy controls), 66.1% ± 2.4 (no DR), and 63.2% ± 2.6 (NPDRP) (p < 0.001). All groups were similar in terms of CT values (p = 0.296). The cut-off value for CVI in predicting retinopathy was 64.7%. Hypertension and current smoking were found to be more frequent in diabetic patients with CVI < 64.7% compared to those with CVI > 64.7%.

CVI tends to be lower in diabetic patients with or without DR compared to healthy controls. Moreover, patients with DR have a lower CVI than those without DR. CVI can be considered an early and sensitive biomarker for the onset of DR.