Effect of image averaging on optical coherence tomography angiography data in eyes with branch retinal vein occlusion.

Abstract

To investigate the effect of image averaging on qualitative and quantitative assessments of optical coherence tomography angiography (OCTA) images from eyes of patients with branch retinal vein occlusion (BRVO). Macular OCTA images of 33 eyes of 33 patients with BRVO were obtained using the HS100 HR-SD-OCT system (Canon, Inc.). For each eye, five OCTA cube scans were obtained with a 3 × 3mm scan protocol, and the data were averaged and compounded into a single high image quality cube data using built-in software. Pre- and post-averaging images were compared qualitatively and quantitatively in superficial capillary plexus (SCP) and deep capillary plexus (DCP) OCTA image slabs. After averaging, all OCTA images showed marked improvement in image quality with less background noise and better vessel continuity. The number of microaneurysms in both the SCP and DCP was larger in single images than in averaged images. A significant increase in the detection rate of capillary telangiectasia in the DCP was noted after image averaging. The number of eyes with disrupted foveal avascular zone (FAZ) decreased significantly after averaging (P = .0253). Five eyes (15.2%) with a disrupted FAZ on the single image showed an intact FAZ after averaging. Vessel length density (VLD) and fractal dimension (FD) significantly decreased and vessel diameter index (VDI) increased after averaging, while significant changes were not observed in vessel density (VD) in both the SCP and DCP. In the SCP, lower VD, VLD, and fractal dimension were significantly correlated with worse visual acuity. OCTA averaging has a significant effect on qualitative and quantitative assessments in eyes with BRVO.