Quantification and Repeatability of Vessel Density and Flux as Assessed by Optical Coherence Tomography Angiography

• Published in: Translational vision science & technology Vol. 8; no. 3; p. 3
• Main Authors: Pappelis, Konstantinos, Jansonius, Nomdo M
• Format: Journal Article
• Language: English
• Published: United States The Association for Research in Vision and Ophthalmology 01.05.2019
• Subjects: repeatability; perfusion; OCT-A; vessel density; test-retest
• DOI: 10.1167/tvst.8.3.3
• ISSN: 2164-2591

To determine the intrasession repeatability (test-retest variability) of parafoveal and peripapillary perfused capillary density (PCD) and normalized flux index (NFI) as assessed with Canon OCT-HS100 angiography. Pairs of optical coherence tomography angiography (OCT-A) images were obtained from the parafoveal and peripapillary region of 30 eyes of 30 healthy subjects. PCD and NFI were calculated using generic image-processing software. Macular ganglion-cell complex thickness (GCC) and peripapillary retinal nerve fiber layer thickness (RNFLT) were also recorded. Bland-Altman analysis was performed and the coefficient of repeatability (CoR) and intraclass correlation coefficient (ICC) were calculated. Correlations of parafoveal PCD/NFI with GCC and of peripapillary PCD/NFI with RNFLT were also computed. Mean (standard deviation) parafoveal and peripapillary PCD were 40.0% (1.8%) and 44.5% (1.3%), respectively. Corresponding values for NFI were 151.2 (6.8) and 164.2 (3.9). For PCD, ICC was 0.76 for parafoveal and 0.79 for peripapillary measurements; corresponding CoRs were 2.7% and 1.8%. Corresponding values for NFI were 0.62 and 0.67 for ICC and 13.3 and 7.0 for CoR. Average measures ICC was 0.87/0.88 and 0.76/0.80 for the parafoveal/peripapillary PCD and NFI, respectively. PCD and NFI were weakly correlated with GCC ( = 0.39, = 0.035; = 0.33, = 0.077) and moderately correlated with RNFLT ( = 0.43, = 0.017; = 0.55, = 0.002). Repeatability of a commercially available OCT-A with generic image-processing software was good (NFI) to excellent (PCD). Our results indicate that changes surpassing the variability in healthy subjects should be easily detectable in a clinical setting. Repeatability estimates provide information regarding the relevance of changes in retinal perfusion.