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http://dx.doi.org/10.14479/jkoos.2013.18.4.441

Axial Rotation of Toric Soft Lens by Corneal Astigmatism and Change of Posture  

Kim, So Ra (Dept. of Optometry, Seoul National University of Science and Technology)
Kim, Hyun Sun (Dept. of Optometry, Seoul National University of Science and Technology)
Jung, Ga Won (Dept. of Optometry, Seoul National University of Science and Technology)
Park, Hyung Min (Dept. of Optometry, Seoul National University of Science and Technology)
Park, Sang Hee (Dept. of Ophthalmic Optics, Kaya University)
Park, Mijung (Dept. of Optometry, Seoul National University of Science and Technology)
Publication Information
Journal of Korean Ophthalmic Optics Society / v.18, no.4, 2013 , pp. 441-447 More about this Journal
Abstract
Purpose: The present study was conducted to investigate the axial rotations of toric soft lens during the change of lens wearer's posture, and the relationship between its rotation and corneal astigmatism. Methods: The amount, direction, and speed of toric soft contact lens rotation were measured for 42 eyes (aged 20s) with the rule astigmatism in the straight and lying postures, and it compared between their changes according to corneal astigmatism. Results: There was no significant difference in the axial rotation of lens for the astigmatism prescription between the straight and lying postures. However, the rotation angle was significantly different according to the posture of lens wearer. Rotating directions in straight posture were nasal direction for 20 eyes and temporal direction for 22 eyes. In lying posture, lenses of most wearers were rotated to a direction of lying posture, and the initial rotating speed was very fast in initial wearing for -0.75 D toric lenses, but consistency for -1.25 D toric lenses. The rotation angle in lying posture showed significantly different according to the amount of corneal astigmatism, the lens speed was also significantly different according to the wearing time but not the amount of corneal astigmatism. Conclusions: The axial rotation of toric soft lens was different by the lens wearer's posture and its amount was the greater with the higher degree of corneal astigmatism. Thus, these factors should be considered for the development of toric lens design.
Keywords
Toric soft contact lens; Total astigmatism; Corneal astigmatism; Rotation angle; Rotation speed;
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