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KMID : 1159320150170040481
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Korean Journal of Vision Science
2015 Volume.17 No. 4 p.481 ~ p.491
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A Study on Importance of Refraction for the Exact Measurement of Lateral Pho
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Kim Jung-Hee
Lee Sun-Mi
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Abstract
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Purpose: In this study, changes in the degree of lateral phoria in myopic astigmatism eyes based on the correction of spherical lens, cylindrical lens and astigmatism axis were investigated.
Methods: The subjects’ degree of refractive error and lateral phoria were completely corrected, after measuring the spherical lens, cylindrical lens, and changes in the degree of lateral phoria with various cylindrical lens axes.
Results: Changes in the degree of lateral phoria in the eye with myopic astigmatism based on the degree of refractive error correction are as follows: When spherical lens was hyper-corrected, the degree of exophoria decreased with a statistically
significant difference(p<0.05), and the degree of esophoria significantly increased only when it was hyper-corrected by as much as 1.00D(p=0.016). When spherical lens was hypo-corrected, the degree of exophoria increased and the degree of esophoria decreased, but the difference was statistically insignificant(p>0.05). The degree of exophoria according to the correction of astigmatism decreased, regardless of the hyper- or hypo- correction of astigmatism and changes in the astigmatism axis, but the difference was statistically insignificant(p>0.05). The degree of esophoria according to the
correction of astigmatism increased when astigmatism was hyper- and hypo- corrected, but the change according to the correction amount of astigmatism was statistically insignificant. The degree decreased when the astigmatism axis was moved 5°, 10°, and 15° clockwise(right direction), and also decreased with the 5°, 10°, and 15° counterclockwise(left direction) movements, but the change in the degree of esophoria based on the astigmatism axis correction was statistically insignificant (p>0.05).
Conclusions: The degree of lateral phoria can changed by incorrectly corrective spherical lens, cylinder lens, and cylindrical lens axis direction. Therefore the lateral phoria must be measured through the degree of astigmatism and astigmatism axis tests by using a cross cylinder and the balancing test. After the refractive power was corrected based on the working test, the lateral phoria prescription must be adjusted accordingly.
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KEYWORD
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degree of lateral phoria, degree of refractive error, balancing test
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