Using OCT Angiography as a Biomarker of Retinopathy Severity in Patients with Diabetes

Abstract

Background and Hypothesis: Diabetic retinopathy (DR), the leading microvasculature and blindness-causing complication of diabetes mellitus, can be diagnosed and monitored using optical coherence tomography angiography (OCT-A) to visualize all retinal vasculature layers with greater resolution and limited invasiveness compared to the established technique of fluorescein angiography. We hypothesize that OCT-A can be used as a biomarker to correlate retinal vessel density (VD) from OCT-A with clinical severity of DR, visual acuity, and patient demographics as well as track anti-vascular endothelial growth factor (VEGF) treatment efficacy. 
 Methods: This retrospective cohort study analyzed the automatically quantified VDs of the superficial vascular complex (SVC) and deep vascular complex (DVC), including the whole, foveal, and parafoveal VDs, on quality OCT-A scans in patients with diagnosed DR. A multivariate linear regression and ANOVA analysis was completed to compare VDs to DR severity, visual acuity, and demographic factors in patients with at least one quality OCT-A scan. A linear mixed analysis was performed to determine how VD was affected by whether anti-VEGF therapy was given to patients with OCT-A scans at two or more different timepoints. 
 Results: There was found to be a positive correlation of the VDs in both the SVC whole and parafoveal VD and DVC parafoveal VD with decreased DR severity and increased visual acuity in the cross-sectional analysis (p ≤0.001). The DVC whole VD was also positively correlated with increased visual acuity (p<0.001). There was no difference in the VDs associated with anti-VEGF treatment over time. 
 Conclusions and Potential Impact: OCT-A shows promise for the diagnosis and monitoring of DR as a biomarker for disease severity which correlates with visual acuity. Anti-VEGF did not show significant change in VD in DR patients. Longer follow-up periods may be needed to elaborate on the long-term effects of anti-VEGF.

Retinal vascular morphological characteristics in diabetic retinopathy: an artificial intelligence study using a transfer learning system to analyze ultra-wide field images

“…Compared with healthy subjects, DR patients had reduced Df values, vessel density and vascular branches, showing a trend toward vascular atrophy and occlusion, which was in line with previous studies. Previous researchers used OCTA to quantify the microvascular density in the macular region, confirming the decrease in vascular density and the increase in avascular area in DR patients [4][5][6][23][24] . Reduced vessel angle indicated increased retinal vascular rigidity and decreased compliance [25] .…”

“…This may be partly due to differences in grouping methods. For instance, Grag et al [6] and Scheive et al [24] classified DR patients into three groups: mild, moderatesevere NPDR, and PDR, whereas the present study did not include patients with PDR to ensure the accuracy of the overall vascular segmentation. Laser Doppler retinal flowmetry also confirmed decreased blood flow in PDR patients, in comparison with NPDR and pre-PDR [27] .…”