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Correcting magnification error in foveal avascular zone area measurements of optical coherence tomography angiography images with estimated axial length

Dutt, Deepaysh DCS; Yazar, Seyhan; Charng, Jason; Mackey, David A; Chen, Fred K; Sampson, Danuta M; (2022) Correcting magnification error in foveal avascular zone area measurements of optical coherence tomography angiography images with estimated axial length. Eye and Vision , 9 (1) , Article 29. 10.1186/s40662-022-00299-x. Green open access

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Abstract

Background: To generate and validate a method to estimate axial length estimated (ALest) from spherical equivalent (SE) and corneal curvature [keratometry (K)], and to determine if this ALest can replace actual axial length (ALact) for correcting transverse magnification error in optical coherence tomography angiography (OCTA) images using the Littmann-Bennett formula. Methods: Data from 1301 participants of the Raine Study Gen2-20 year follow-up were divided into two datasets to generate (n = 650) and validate (n = 651) a relationship between AL, SE, and K. The developed formula was then applied to a separate dataset of 46 participants with AL, SE, and K measurements and OCTA images to estimate and compare the performance of ALest against ALact in correcting transverse magnification error in OCTA images when measuring the foveal avascular zone area (FAZA). Results: The formula for ALest yielded the equation: ALest = 2.102K − 0.4125SE + 7.268, R2 = 0.794. There was good agreement between ALest and ALact for both study cohorts. The mean difference [standard deviation (SD)] between FAZA corrected with ALest and ALact was 0.002 (0.015) mm2 with the 95% limits of agreement (LoA) of − 0.027 to 0.031 mm2. In comparison, mean difference (SD) between FAZA uncorrected and corrected with ALact was − 0.005 (0.030) mm2, with 95% LoA of − 0.064 to 0.054 mm2. Conclusions: ALact is more accurate than ALest and hence should be used preferentially in magnification error correction in the clinical setting. FAZA corrected with ALest is comparable to FAZA corrected with ALact, while FAZA measurements using images corrected with ALest have a greater accuracy than measurements on uncorrected images. Hence, in the absence of ALact, clinicians should use ALest to correct for magnification error as this provides for more accurate measurements of fundus parameters than uncorrected images.

Type: Article
Title: Correcting magnification error in foveal avascular zone area measurements of optical coherence tomography angiography images with estimated axial length
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1186/s40662-022-00299-x
Publisher version: https://doi.org/10.1186/s40662-022-00299-x
Language: English
Additional information: © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
Keywords: Science & Technology, Life Sciences & Biomedicine, Ophthalmology, OCTA, Keratometry, Spherical equivalent, Axial length, Littmann-Bennett formula, REFRACTIVE ERROR, SIZE, FUNDUS, ACCOMMODATION, PREVALENCE, AGREEMENT, OBJECT, COHORT, BIRTH, EYE
UCL classification: UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10154334
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