Optical coherence tomography angiography microvascular changes in diabetics without diabetic retinopathy

The purpose of this study was to analyze the retinal vasculature of diabetic eyes without clinical retinopathy in order to detect microvascular abnormalities, comparing them to that of healthy nondiabetic control eyes.

This is a prospective, cross-sectional study including 40 patients (76 eyes). Twenty patients (40 eyes) were diabetics with no diabetic retinopathy group (NDRG). The twenty other patients (36 eyes) were nondiabetic and constituted the control group (CG). Images were obtained using the AngioVue optical coherence tomography angiography (OCTA) software of RTVue XR spectral-domain OCT device. We performed 3 mm × 3 mm and 6 mm × 6 mm scans to evaluate the foveolar avascular zone (foveal) size, a remodeling of the FAZ, microaneurysms, vessel tortuosity, and superficial vascular density. All statistics were performed using IBM SPSS statistics (version 21).

The average FAZ size was 314.6 ± 15.3 μm in the NDRG versus 291.5 ± 14.1 in the CG. The difference was not significant (P = 0.56). FAZ remodeling was noted in 40% of eyes in the NDRG and in 2.8% of eyes in the CG (P = 0.0001). Flow alteration zones (nonperfusion zones) were seen in 77.5% in the NDRG (P = 0.0001). Microaneurysms were present only in the NDRG (70% of eyes). Parafoveolar vascular density was 52.8% ± 0.7% in the NDRG and 54.1% ± 0.25% in the CG but without significant difference (P = 0.206), and vascular tortuosity was significantly present in the NDRG with 32.5% of eyes versus 11.1% of eyes in the CG (P = 0.003).

OCTA is a promising tool to identify microvascular changes in the diabetic retina before clinically visible retinopathy occurrence. It may identify in the future individuals at risk of developing retinopathy and therefore those needing a better balance of diabetes.