Automation improves repeatability of retinal oximetry measurements

Róbert Arnar Karlsson*, Ólöf Birna Ólafsdottir, Védis Helgadóttir, Soumaya Belhadj, Þórunn Scheving Elíasdóttir, Einar Stefánsson, Sveinn Hákon Harðarson

*Corresponding author for this work

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Purpose Retinal oximetry is a technique based on spectrophotometry where images are analyzed with software capable of calculating vessel oxygen saturation and vessel diameter. In this study, the effect of automation of measurements of retinal vessel oxygen saturation and vessel diameter is explored. Methods Until now, operators have had to choose each vessel segment to be measured explicitly. A new, automatic version of the software automatically selects the vessels once the operator defines a measurement area. Five operators analyzed image pairs from the right eye of 23 healthy subjects with semiautomated retinal oximetry analysis software, Oxymap Analyzer (v2.5.1), and an automated version (v3.0). Inter- and intra-operator variability was investigated using the intraclass correlation coefficient (ICC) between oxygen saturation measurements of vessel segments in the same area of the retina. Results For semiautomated saturation measurements, the inter-rater ICC was 0.80 for arterioles and venules. For automated saturation measurements, the inter-rater ICC was 0.97 for arterioles and 0.96 for venules. For semiautomated diameter measurements, the inter-rater ICC was 0.71 for arterioles and venules. For automated diameter measurements the inter-rater ICC was 0.97 for arterioles and 0.95 for venules. The inter-rater ICCs were different (p < 0.01) between the semiautomated and automated version in all instances. Conclusion Automated measurements of retinal oximetry values are more repeatable compared to measurements where vessels are selected manually.

Original languageEnglish
Article numbere0260120
JournalPLoS ONE
Issue number12 December
Publication statusPublished - Dec 2021

Bibliographical note

University of Iceland Research Fund (RAK), Icelandic Research Fund (VH), Marie Skłodowska-Curie Actions (SB). Other authors received no funding related to this study (OBO, TSE, SHH). The funders provided support in the form of salaries for authors RAK, VH and SB, but did, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the “author contributions” section.

Publisher Copyright:
Copyright: © 2021 Karlsson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Other keywords

  • Oximetry / methods
  • Oxygen / analysis
  • Retinal Vessels / chemistry
  • Software


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