Correlation of En Face OCTA Averaging versus Single Image Quantitative Measurements with Retinal Vein Occlusion Visual Outcomes

Abstract

Purpose : To demonstrate the effect of correlating multiple en face imaging averaging of quantitative metrics of the retinal microvasculature using optical coherence tomography angiography (OCTA) in Retinal Vein Occlusion (RVO) with best corrected visual acuity (BCVA)

Methods : Eyes with unilateral RVO and a normal contralateral eye were imaged in this cross-sectional study. Images had signal strength >7, uniform illumination, foveal centration, and minimal artifact or saccades. Spectral Domain OCTA images were acquired on each eye 5 times with the Cirrus 5000 Angioplex 3x3mm scan pattern (Carl Zeiss Meditec, Dublin, CA). Automated segmented scans were averaged with registration for the superficial retinal layer (SRL) and deep retinal layer (DRL) (Figure 1). Quantitative parameters including the size and circularity of the foveal avascular zone (FAZ) and parafoveal vessel density (VD) of the averaged versus single image were correlated to logMAR BCVA. Pearson correlation coefficient was performed to compare the average versus single groups; and univariate and stepwise multivariate linear regression with clustering on the individual level were performed to correlate quantitative metrics to BCVA

Results : Twenty eyes (10 patients, 5 male) with 6 having BRVO, 2 with HRVO and 2 with CRVO and mean age of 64.3 (range 47-88) were included. Mean LogMAR BCVA of the contralateral normal eyes was 0.056 (±std 0.064, Snellen 20/23 ±std 3.5); and the involved eye was 0.29 (±std 0.29, Snellen 20/49.1 ±std 36.8). Averaged VD of the SRL (p=0.02) and DRL (p=0.04) Inner Ring and SCP (p<0.01) and DCP (p<0.00) total VD was significantly less than the single image. In the multivariate linear regression when including all OCTA parameters that were significantly associated with BCVA on univariate analysis, overall, averaging resulted in an increased R² value (from 0.93 to 0.95, for single and averaged groups, respectively). FAZ circularity was associated with BCVA with single images (coefficient -0.96, p=0.002), but not with averaging (p=0.063)

Conclusions : Averaging of en face OCTA images improves the clarity of vessels and may allow for more accurate quantification of VD and FAZ parameters. BCVA is associated with VD, but averaging does not necessarily improve the ability to accurately define this association compared to a single OCTA scan

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Figure 1. Averaged vs Single Images of the SRL and DRL