Abstract
Purpose :
To investigate the intravisit repeatability of sequential optic disc and macular OCT Angiography scans and assess factors affecting the variability of retinal vessel caliber measurements between sequential scans.
Methods :
A cross-sectional study was performed to examine variation of vascular caliber measurements across sequential OCTA en face images. 48 eyes of 28 patients were imaged in both the disc and macula twice using the Heidelberg Spectralis OCT2 (Heidelberg, Germany). Two independent masked graders measured vessel caliber of the five highest resolution veins and arteries involving all peripapillary quadrants centered around the optic disc and involving all perimacular quadrants centered around the fovea. Multiple measurements were made on each vessel segment and averaged to obtain a measure of caliber for each vessel. Care was taken to ensure that the vessel segment measured did not branch. The intraclass correlation (ICC) of caliber measures was calculated between graders and between repeat OCTA images by the same grader. ICC values were calculated separately in subgroups defined by sex, race, glaucoma status, diabetes, hypertension, image quality, pseudophakia, vessel length, scan location, and age. In addition, we estimated the standard deviation of the difference of caliber measures on the same vessel in the two images.
Results :
A total of 8400 measurements of 420 vessels of 84 OCTA images were included in the analysis. Inter-grader agreement was excellent at 0.90. The ICC for repeated OCTA images was 0.96 for all images. The standard deviation for the difference between caliber measures on the same vessel from two different images was 7.34 microns. The standard deviation for differences in subgroups ranged from approximately 4.7 to 8.9 microns. Sex, race, glaucoma, diabetes, image quality, vessel length, age, and scan location all had significant differences in the standard deviations of vessel width.
Conclusions :
There is low variability in vessel caliber across repeated OCTA en face images. Demographic factors such as disease state and age may affect the repeatability of vessel width measurements, as may image quality. Further recruitment and analysis will allow for a multivariable analysis of factors affecting repeatability.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.