Correlation of Quantitative Measurements with Diabetic Disease Severity Using Multiple En Face OCT Angiography Image Averaging

Purpose: To evaluate the effect of averaging en face OCT angiography (OCTA) images on quantitative measurements of the retinal microvasculature and their correlation to diabetic retinopathy (DR) disease severity. Design: Cross-sectional cohort study. Participants: One hundred five eyes (65 patients) comprising 28 eyes from 19 healthy, aged-matched control participants, 14 eyes from 9 diabetics without DR, and 63 eyes from 37 diabetics with varying levels of DR. Methods: Spectral-domain CIRRUS 5000 (Carl Zeiss Meditec, Dublin, CA) OCTA images with no macular edema or significant motion artifact were acquired 5 times with the 3 x 3-mm scan pattern. En face images of the superficial retinal layer (SRL) and deep retinal layer were registered and averaged. Vessel length density (VLD), perfusion density (PD), and foveal avascular zone (FAZ) parameters were measured on averaged versus single OCTA images. Main Outcome Measures: Univariate and multivariate linear regression correlated quantitative metrics to DR severity and best-corrected visual acuity (BCVA). Results: Eighty-four eyes (55 patients) met the inclusion criteria. Almost uniformly, lower VLD and PD parameters were associated significantly with worse DR severity and BCVA. Multivariate linear regression for DR severity resulted in an R-2 value of 0.82 and 0.77 for single and averaged groups, respectively. No variables remained associated significantly with DR severity in multivariate analysis with single images, but in averaged images, increased superior SRL PD significantly predicted worse DR severity (coefficient, 52.7; P = 0.026). Multivariate linear regression for BCVA had an R-2 value of 0.42 and 0.47 for single and averaged groups, respectively. Foveal avascular zone size was not associated with DR severity when single OCTA images (P = 0.98) were considered, but was highly associated when using averaged images (coefficient, 6.18; P < 0.001). Foveal avascular zone size was predictive for logarithm of the minimum angle of resolution BCVA with averaged images (0.21; P = 0.004), but not with single images (P = 0.31). Conclusions: Averaging of en face OCTA images improves the visualization of capillaries, particularly increasing the clarity of the FAZ borders, and therefore improves the correlation of vessel density and FAZspecific parameters to DR severity and BCVA. (C) 2020 by the American Academy of Ophthalmology