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Rie Oda, Kazuhiko Mori, Kengo Yoshii, Yoko Ikeda, Morio Ueno, Haruna Yoshikawa, Yuko Maruyama, Noriko Koizumi, Shigeru Kinoshita; Rotation angle of the optic disc and clinical features in normal Japanese eyes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1007.
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© ARVO (1962-2015); The Authors (2016-present)
Optic disc shape is known to be biomechanically important, yet there have been few reports about parameters relevant to the optic-disc rotation angle in normal eyes. In this study, we performed multivariate linear regression analysis to investigate the relationship between optic disc parameters including rotation angle and clinical features in normal eyes.
This study involved 580 eyes of 580 normal Japanese subjects (216 males and 364 females; mean age: 51.4±14.4 years). Inclusion criteria included subjects who 1) visited the outpatient clinic of Kyoto Prefectural University of Medicine, Kyoto, Japan between June 2005 and December 2008, 2) were diagnosed by glaucoma specialists as normal based on several ophthalmic examinations, and in whom 3) reliable disc photographs could be obtained. In all eyes, disc photographs were imported to image processing software (Image J 1.48q, NIH, Bethesda, MD). The optic disc was approximated as an ellipse, and the major and minor axis were determined. The line connecting the optic disc center and macula was regarded as the baseline, and the optic-disc rotation angle (DRA) was defined as the angle between the major axis and baseline. Eccentricity and averaged radius of the ellipse were also measured, and disc-macula to disc diameter ratio (DM/DD) was calculated by the ratio of the length of disc center to macula and averaged radius. Optic disc area (DA) was analyzed by retinal tomography (HRT-2; Heidelberg Engineering GmbH, Heidelberg, Germany). The clinical features of age, sex, refractive error (RE), corneal radius (CR), axial length (AL) were also measured. Multivariate linear regression analysis was performed, regarding DRA as an objective variable, and eccentricity, ellipticity, DM/DD, DA, AL, age, sex, RE, and CR as explanatory variables. Right-eye data was selected if both eyes were available.
In all eyes, the mean DRA, eccentricity, and DM/DD were 12.7±34.1, 0.43±0.16, and 2.73±0.33, respectively. Linear regression analysis results showed that age (p=0.040) and AL (p=0.005) were significant explanatory variables for DRA.
DRA was not significantly related to optic disc size, but was related to AL and subject age.
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