Detection of early microvascular changes in diabetic patients with OCTA

Abstract

Purpose : Controversy exists whether optical coherence tomography angiography (OCTA) is able to detect preclinical retinal microvascular alterations in diabetic patients. We performed a cross-sectional analysis of the German Diabetes Study and analyzed type 1 and type 2 diabetic patients with regard to early changes in retinal vasculature.

Methods : In a cross-sectional analysis oft the German Diabetes Study, the flow density of 74 diabetic and 52 control subjects in the macular region was analyzed by OCTA (Spectralis®, Heidelberg Engineering®) (10x10°, 512 A-scans, EDI mode, centered on the fovea centralis). After segmentation control, en face OCTA images of superficial (SVP), intermediate (IVP), and deep vascular plexus (DVP) were binarized in ImageJ using Otsu's thresholding method and flow density (proportion of white pixels to total pixel count) was calculated. Ultra-widefield fundus images were captured (Optos®, Optmap, Marlborough, MA, USA) and the stage of diabetic retinopathy was classified according to the International Clinical Diabetic Retinopathy Disease Severity Scale. Statistical analysis was performed using PROC MIXED (SAS,V 9.4,Cary, North Carolina, USA), age- and sex-adjusted.

Results : 47 patients with type 2 diabetes (T2DM) (32 male, age 58.6±11.9 (SD) years (Y), diabetes duration 6.9±2.8 Y), 27 patients with type 1 diabetes (T1DM) (14 male, 42.6±10.6 Y, diabetes duration 7.7±2.6 Y), and 52 control subjects (26 male, 42±15.6 Y) were evaluated. 1 subject from T2DM (2.1%) and T1DM (3.7%) showed mild nonproliferative diabetic retinopathy. The flow density for T2DM in SVP was 0.25±0.04, which was lower than in controls (0.28±0.04; p=0.0433). The other values for IVP (0.32±0.06) and DVP (0.33±0.05) did not differ from controls (IVP: 0.36±0.05; p=0.2365, DVP: 0.37±0.06; p=0.0507). The same was true for T1DM (SVP: 0.27±0.05; p=0.1760, IVP: 0.35±0.05; p=0.6661 and DVP: 0.36±0.06; p=0.2812). The decrease in flow density with age (per year of life: SVP: -0.00086, IVP -0.00163, DVP -0.00147, p each <.0001) was taken into account.

Conclusions : With similar duration of diabetes, T2DM, in contrast to T1DM, have lower flow density in SVP compared with controls. Accordingly, capillary vascular changes in T2DM are clearly detectable with OCTA even without DR. Overall, there is an age-dependent decrease in flow density, so future studies should always use age-adjusted data.

This is a 2021 ARVO Annual Meeting abstract.