Aims To compare the intrasession repeatability of peripapillary and macular vessel density measurements of optical coherence tomography angiography (OCTA) in normal and glaucoma eyes, and to evaluate the effect of signal strength of OCTA scans on the repeatability.
Methods In a cross-sectional study, three optic nerve head scans each of 65 eyes (30 normal, 35 glaucoma eyes) and three macular scans each of 69 eyes (35 normal, 34 glaucoma eyes) acquired in the same session with OCTA were analysed. Repeatability was assessed using within-subject coefficient of repeatability (CRw) and variation (CVw). Effect of signal strength index (SSI) on repeatability was evaluated with repeated-measures mixed-effects models.
Results CRw (%) and CVw (%) of peripapillary measurements in normal eyes ranged between 3.3 and 7.0, and 2.5 and 4.4 respectively, and that in glaucoma eyes between 3.5 and 7.1, and 2.6 and 6.6. For the macular, these measurements ranged between 4.1 and 6.0, and 3.3 and 4.7 in normal eyes and 4.3 and 6.9, and 3.7 and 5.6 in glaucoma eyes. Repeatability estimates of most measurements were similar in normal and glaucoma eyes. Vessel densities of both peripapillary and macular regions significantly increased with increase in SSI of repeat scans (coefficients ranging from 0.15 to 0.38, p<0.01 for all associations).
Conclusions Repeatability estimates of OCTA measured peripapillary and macular vessel densities were similar in normal eyes and eyes with glaucoma. SSI values of the scans had a significant effect on the repeatability of OCTA with the vessel density values increasing in scans with higher SSI values.
- optical coherence tomography angiography
- intra-session repeatability
- peripapillary vessel density
- macular vessel density
- signal strength index
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Contributors HLR was involved in conception and design, acquisition of data or analysis and interpretation of data; drafting the article or revising it critically for important intellectual content; and final approval of the version to be published. All the authors have contributed substantially to conception and design, acquisition of data and interpretation of data; revising it critically for important intellectual content; and final approval of the version to be published.
Competing interests HLR is a consultant for Pfizer, Santen and Cipla, RNW is a consultant for Aerie Pharmaceuticals, Allergan, Alcon, Eyenovia, Bausch & Lomb, Sensimed and Unity, KM is a consultant for Santen and Sensimed and CABW is a consultant for Alcon, Allergan, Santen and Pfizer. RNW has received financial support in form of instruments or research funding from Optovue, Topcon, Carl Zeiss, Heidelberg Engineering and Genentech, KM has received financial support in form of instruments or research funding from Topcon and Alcon, and CABW has received financial support in form of instruments or research funding from Alcon.
Patient consent Obtained.
Ethics approval The Ethics Committee of Narayana Nethralaya.
Provenance and peer review Not commissioned; externally peer reviewed.
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