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KMID : 1011420190240040419
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Journal of Korean Ophthalmic Optics Society
2019 Volume.24 No. 4 p.419 ~ p.426
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Distribution of Astigmatism and Symmetrical and Asymmetrical Astigmatism at Far and Near Distance
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Shim Moon-Sik
Shim Hyun-Suk
Kim Young-Cheong
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Abstract
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Purpose: The purpose of this study was to investigate the distribution and changes in binocular astigmatism, symmetric astigmatism (S-A), and asymmetric astigmatism (A-A) according to sex and age during far and near distance viewing.
Methods: An auto-refraction test using an Nvision-K 5001 (Shinnippon, Japan), far distance test at 5 m, and near distance test 40 cm were performed. Astigmatism was divided into left and right eyes at far and near distances. Individuals with over C-0.50 D were enrolled as subjects. Astigmatism was classified as S-A when the sum of the left and right astigmatic axis was 180 ± 15° and A-A when otherwise.
Results: Of the total 800 subjects, binocular astigmatism was present in 99.25%. Astigmatism in the far and near distance in the right eye wasere C-0.62 ± 0.55 D and C?0.68 ± 0.60 D, respectively, and in the left eye, C?0.68 ± 0.57 D and C?0.75 ± 0.64 D, respectively. Astigmatism showed a statistically significant difference between left and right eyes and high correlation and high correlation except for women during near distance viewing. Values above Cyl-0.50 D in binocular astigmatism were 59.32%:40.68% (S-A:A-A) at far distance viewing and 54.52%:45.48% at near distance viewing. S-A was highest in subjects less than 10 years old (69.57%) during far distance viewing and those in their 20s (68.83%) during near distance viewing. A-A was highest in the over 60s age group (55.56%) during far distance viewing and those in their 30s (68.97%) during near distance viewing. The S-A was higher during far and near distance viewing than the A-A, but the S-A decreased and the A-A increased during near distance viewing at all ages except for those in their 20s.
Conclusions: There was a significant difference in the amount of astigmatism during far and near distance viewing. During near distance viewing, in subjects in their 20s, S-A increased, and in those 30 and older, A-A increased. If an existing glasses wearer has asthenopia and decreased visual acuity, it is believed that it is necessary to diagnose astigmatism during near distance viewing by performing an astigmatism test at a near distance.
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KEYWORD
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Astigmatism axis, Symmetrical astigmatism, Asymmetrical astigmatism, Near distance test, Far distance test
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