Quantitative analysis of changes in the retinal microvasculature in uveitis using spectral domain optical coherence tomography angiography (SD-OCTA)

Abstract

Purpose : To investigate quantitative indices of retinal perfusion density and morphology in uveitis using SD-OCTA.

Methods : Cross-sectional, observational study of healthy subjects and otherwise healthy adult subjects with anterior, posterior, or pan-uveitis from the USC Eye Institute and affiliated clinics. A prototype SD-OCTA device (Cirrus, Carl Zeiss Meditec, Dublin, CA) with intensity-based optical microangiography (OMAG) algorithm was used to generate at least one 3x3 mm OCTA image centered on the fovea for each eye of interest. Non-segmented and segmented OCTA images were analyzed using a semi-automated program that converted the 2D grayscale en face OCTA images into binarized (Fig. 1A-C) and skeletonized (Fig. 1D-F) images. The density and morphology of the retinal microvasculature was then quantified using these images as the skeleton density (SD), vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI). The Student’s t-test or analysis of variance (ANOVA) with post hoc Tukey Honest Significant Difference (HSD) tests were used for all statistical analyses.

Results : Twenty-three eyes with uveitis and 14 eyes of healthy subjects were studied. In the non-segmented analysis, uveitic eyes had significantly lower SD (0.087±0.014 vs 0.102±0.005; P<0.001), VD (0.365±0.057 vs 0.423±0.020; P=0.001), and FD (1.691±0.038 vs 1.722±0.008; P<0.01), compared to healthy eyes. In the superficial retinal layer, uveitis eyes still had significantly lower SD (0.083±0.010 vs 0.098±0.003; P<0.001), VD (0.362±0.044 vs 0.426±0.019; P<0.001), and FD (1.687±0.025 vs 1.717±0.006; P<0.001), compared to healthy eyes. The same finding was true for the deep retinal layer analysis (P<0.05). VDI was greater in uveitic eyes compared to healthy eyes (e.g. 4.198±0.085 vs 4.160±0.054 for the non-segmented layer; P=0.13), but did not approach significance in any retinal segment.

Conclusions : Quantitative changes in the retinal microvasculature of uveitic eyes can be detected using measurements of SD, VD, FD, and VDI. Lower SD, VD, and FD, as well as larger VDI on OCTA analysis may indicate retinal microvascular compromise in uveitis.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.