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

Deepaysh D.C.S. Dutt; Seyhan Yazar; Jason Charng; David A. Mackey; Fred K. Chen; Danuta M. Sampson

doi:10.1186/s40662-022-00299-x

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

Deepaysh D.C.S. Dutt, Seyhan Yazar, Jason Charng, David A. Mackey, Fred K. Chen, Danuta M. Sampson

Research output: Contribution to journal › Article › peer-review

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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.

Original language	English
Article number	29
Journal	Eye and Vision
Volume	9
Issue number	1
DOIs	https://doi.org/10.1186/s40662-022-00299-x
Publication status	Published - Dec 2022

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@article{187565b9d7534731b02c9be209ddd830,

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

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.",

keywords = "Axial length, Keratometry, Littmann-Bennett formula, OCTA, Spherical equivalent",

author = "Dutt, {Deepaysh D.C.S.} and Seyhan Yazar and Jason Charng and Mackey, {David A.} and Chen, {Fred K.} and Sampson, {Danuta M.}",

note = "Funding Information: We are grateful to the Raine Study Gen2-20 year follow-up participants and their families for their ongoing involvement in the study and we thank the Raine Study and Lions Eye Institute research staff for cohort coordination and data collection. We also thank the NHMRC for their long-term contribution to funding the study over the last 30 years. The core management of the Raine Study is funded by The University of Western Australia, Curtin University, Telethon Kids Institute, Women and Infants Research Foundation, Edith Cowan University, Murdoch University, The University of Notre Dame Australia, and the Raine Study Medical Research Foundation. The eye data collection of the Raine Study Gen2-20 year follow-up was funded by NHMRC Grant 1021105, Ophthalmic Research Institute of Australia, Alcon Research Institute, Lions Eye Institute, and the Australian Foundation for the Prevention of Blindness. Funding Information: We are grateful to the Raine Study Gen2-20 year follow-up participants and their families for their ongoing involvement in the study and we thank the Raine Study and Lions Eye Institute research staff for cohort coordination and data collection. We also thank the NHMRC for their long-term contribution to funding the study over the last 30 years. The core management of the Raine Study is funded by The University of Western Australia, Curtin University, Telethon Kids Institute, Women and Infants Research Foundation, Edith Cowan University, Murdoch University, The University of Notre Dame Australia, and the Raine Study Medical Research Foundation. The eye data collection of the Raine Study Gen2-20 year follow-up was funded by NHMRC Grant 1021105, Ophthalmic Research Institute of Australia, Alcon Research Institute, Lions Eye Institute, and the Australian Foundation for the Prevention of Blindness. Publisher Copyright: {\textcopyright} 2022, The Author(s).",

year = "2022",

month = dec,

doi = "10.1186/s40662-022-00299-x",

language = "English",

volume = "9",

journal = "Eye and Vision",

issn = "2326-0254",

publisher = "BioMed Central",

number = "1",

}

TY - JOUR

T1 - Correcting magnification error in foveal avascular zone area measurements of optical coherence tomography angiography images with estimated axial length

AU - Dutt, Deepaysh D.C.S.

AU - Yazar, Seyhan

AU - Charng, Jason

AU - Mackey, David A.

AU - Chen, Fred K.

AU - Sampson, Danuta M.

N1 - Funding Information: We are grateful to the Raine Study Gen2-20 year follow-up participants and their families for their ongoing involvement in the study and we thank the Raine Study and Lions Eye Institute research staff for cohort coordination and data collection. We also thank the NHMRC for their long-term contribution to funding the study over the last 30 years. The core management of the Raine Study is funded by The University of Western Australia, Curtin University, Telethon Kids Institute, Women and Infants Research Foundation, Edith Cowan University, Murdoch University, The University of Notre Dame Australia, and the Raine Study Medical Research Foundation. The eye data collection of the Raine Study Gen2-20 year follow-up was funded by NHMRC Grant 1021105, Ophthalmic Research Institute of Australia, Alcon Research Institute, Lions Eye Institute, and the Australian Foundation for the Prevention of Blindness. Funding Information: We are grateful to the Raine Study Gen2-20 year follow-up participants and their families for their ongoing involvement in the study and we thank the Raine Study and Lions Eye Institute research staff for cohort coordination and data collection. We also thank the NHMRC for their long-term contribution to funding the study over the last 30 years. The core management of the Raine Study is funded by The University of Western Australia, Curtin University, Telethon Kids Institute, Women and Infants Research Foundation, Edith Cowan University, Murdoch University, The University of Notre Dame Australia, and the Raine Study Medical Research Foundation. The eye data collection of the Raine Study Gen2-20 year follow-up was funded by NHMRC Grant 1021105, Ophthalmic Research Institute of Australia, Alcon Research Institute, Lions Eye Institute, and the Australian Foundation for the Prevention of Blindness. Publisher Copyright: © 2022, The Author(s).

PY - 2022/12

Y1 - 2022/12

N2 - 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.

AB - 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.

KW - Axial length

KW - Keratometry

KW - Littmann-Bennett formula

KW - OCTA

KW - Spherical equivalent

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U2 - 10.1186/s40662-022-00299-x

DO - 10.1186/s40662-022-00299-x

M3 - Article

C2 - 35909098

AN - SCOPUS:85135188052

SN - 2326-0254

VL - 9

JO - Eye and Vision

JF - Eye and Vision

IS - 1

M1 - 29

ER -

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

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

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