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Variability of scan quality and perfusion density in longitudinal optical coherence tomography angiography imaging
  1. Corey A Smith1,2,
  2. Vanessa L Josey2,
  3. Michael E West2,
  4. Oksana M Dyachok2,
  5. Glen P Sharpe1,
  6. Jayme R Vianna1,2,
  7. Paul E Rafuse1,2,
  8. Lesya M Shuba1,2,
  9. Marcelo T Nicolela1,2,
  10. Balwantray C Chauhan1,2
  1. 1 Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
  2. 2 Nova Scotia Health Authority, Halifax, Nova Scotia, Canada
  1. Correspondence to Dr Corey A Smith, Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada; corey.smith{at}


Background/aims Optical coherence tomography angiography (OCT-A) images are subject to variability, but the extent to which learning impacts OCT-A measurements is unknown. We determined whether there is a learning effect in glaucoma patients and healthy controls imaged with OCT-A.

Methods Ninety-one open-angle glaucoma patients and 54 healthy controls were imaged every 4 months over a period of approximately 1 year in this longitudinal cohort study. We analysed 15°×15° scans, centred on the fovea, in one eye of each participant. Two-dimensional projection images for the superficial, intermediate and deep vascular plexuses were exported and binarised after which perfusion density was calculated. Linear mixed-effects models were used to investigate the association between perfusion density and follow-up time.

Results The mean (SD) age of glaucoma patients and healthy controls was 67.3 (8.1) years and 62.1 (9.0) years, respectively. There was a significant correlation between perfusion density and scan quality in both glaucoma patients (r=0.50 (95% CI 0.42 to 0.58); p<0.05) and healthy controls (r=0.41 (95% CI 0.29 to 0.52); p<0.05). An increase in perfusion density occurred over time and persisted, even after adjustment for scan quality (1.75% per year (95% CI 1.14 to 2.37), p<0.01).

Conclusions Perfusion density measurements are subject to increasing experience of either the operator or participant, or a combination of both. These findings have implications for the interpretation of longitudinal measurements with OCT-A.

  • Glaucoma
  • Imaging

Data availability statement

Data are available on reasonable request.

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Data availability statement

Data are available on reasonable request.

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  • Contributors All authors attest that they meet the current ICMJE criteria for authorship. Conception and design: CAS and BCC. Data acquisition: MEW, OMD and GPS. Analysis and interpretation: all authors. Drafting, revising and final approval of the manuscript: all authors. Guarantor: CAS.

  • Funding This study was supported by grants from the Canadian Institutes of Health Research (PJT159564, BCC), Alcon Research Institute (BCC) and Glaucoma Research Society of Canada (CAS).

  • Competing interests JRV: EadieTech (Consultant); PER: Allergan, Bausch and Lomb (Consultant); LMS: Alcon, Allergan, Basuch and Lomb (Consultant); MTN: Allergan (Consultant and Lecturer), Alcon (Lecturer), Bausch and Lomb (Consultant), Heidelberg Engineering (Equipment Support), Labtican (Consultant), Thea (Consultant); BCC: CenterVue, Heidelberg Engineering, Topcon (Equipment Support)

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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