Aiko Iwase1, Akihiko Sekine2, Jun Suehiro2, Kenji Tanaka1, Yumiko Kawasaki3, Ryo Kawasaki3, Michael J Sinai2, Makoto Araie4. 1. Tajimi Iwase Eye Clinic, Tajimi, Japan. 2. Topcon Corporation, Tokyo, Japan. 3. Department of Public Health, Yamagata University Graduate School of Medical Science, Yamagata, Japan. 4. Kanto Central Hospital of the Mutual Aid Association of Public School Teachers, Tokyo, Japan.
Abstract
Purpose: To report a semiautomated retinal vessel caliber measurement system that measures central retinal artery (vein) equivalent (CRAE [CRVE]) with individual correction for magnification errors under conditions assuming optimal focus. Methods: The focusing condition of the subject eye fundus camera optical system was individually determined by constructing an optical model of each eye applying its refractive error, corneal curvature, and axial length (AL) to Gullstrand's schematic eye, and by adjusting the position of the camera's focusing lenses using each eye's refractive error. Once the focusing condition of the entire optical system was fulfilled, magnification of the fundus images was calculated using paraxial ray tracing. Measurements of CRAE (CRVE) were performed in an annular area centered on the optic disc with magnification-corrected diameter from 1.8 to 2.7 mm. Reproducibility of the measurements of the results using the new method and comparison with those using interactive vessel analysis (IVAN) were performed in normal Japanese eyes. Results: Intra- and interexaminer intraclass correlation coefficient (ICC) for CRAE (CRVE) measurements was greater than 0.978. CRAE (CRVE) using the new method averaged 148.9 ± 10.9 μm (225.0 ± 13.9 μm; mean ± SD, N = 99). Differences between the new method and IVAN were greater with increasing AL (P < 0.001). The new method yielded CRAE (CRVE) in good agreement with IVAN in eyes with AL of approximately 24 mm. However, the new method yielded smaller values in eyes with shorter AL and vice versa. Conclusions: A new accurate and reproducible method to measure CRAE (CRVE) from fundus photographs was reported.
Purpose: To report a semiautomated retinal vessel caliber measurement system that measures central retinal artery (vein) equivalent (CRAE [CRVE]) with individual correction for magnification errors under conditions assuming optimal focus. Methods: The focusing condition of the subject eye fundus camera optical system was individually determined by constructing an optical model of each eye applying its refractive error, corneal curvature, and axial length (AL) to Gullstrand's schematic eye, and by adjusting the position of the camera's focusing lenses using each eye's refractive error. Once the focusing condition of the entire optical system was fulfilled, magnification of the fundus images was calculated using paraxial ray tracing. Measurements of CRAE (CRVE) were performed in an annular area centered on the optic disc with magnification-corrected diameter from 1.8 to 2.7 mm. Reproducibility of the measurements of the results using the new method and comparison with those using interactive vessel analysis (IVAN) were performed in normal Japanese eyes. Results: Intra- and interexaminer intraclass correlation coefficient (ICC) for CRAE (CRVE) measurements was greater than 0.978. CRAE (CRVE) using the new method averaged 148.9 ± 10.9 μm (225.0 ± 13.9 μm; mean ± SD, N = 99). Differences between the new method and IVAN were greater with increasing AL (P < 0.001). The new method yielded CRAE (CRVE) in good agreement with IVAN in eyes with AL of approximately 24 mm. However, the new method yielded smaller values in eyes with shorter AL and vice versa. Conclusions: A new accurate and reproducible method to measure CRAE (CRVE) from fundus photographs was reported.
Authors: Thibaud Mautuit; Pierre Cunnac; Carol Y Cheung; Tien Y Wong; Stephen Hogg; Emanuele Trucco; Vincent Daien; Thomas J MacGillivray; José Labarère; Christophe Chiquet Journal: Diagnostics (Basel) Date: 2022-05-25