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KMID : 1159320130150020101
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Korean Journal of Vision Science
2013 Volume.15 No. 2 p.101 ~ p.111
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A Study on the Spherical Aberration and Astigmatism of Sports Sunglass
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Seo Ji-Keun
Cho Young-Nam
Shim Hyun-Suk
Kim Sang-Hyun
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Abstract
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Purpose: This study was conducted to calculate optical aberration of sport sunglasses. Methods: The spherical aberrations are calculated by homemade ray tracing program and the astigmatism aberrations are by well known analytic formulas. Result and Discussion: The spherical aberrations depend deeply on shape of lens such as front curvature. The spherical aberration of sports sunglasses is lager than that of general eyewear due to high curvature of sport sunglasses, but the amount of aberration is not so much to affect visual life seriously. The critical problem when wearing sports sunglasses is aberration with face form angle(FFA). The FFA of sports sunglasses frame is very larger than that of eyewear frame, and the astigmatic aberration due to FFA which transform spherical lens to toric lens induced over 1 D of size. The FFA related astigmatism can be bigger when standards P.D. is larger than dispensing P.D. Specially, when viewed sideways, we found that the difference of FFA between left and right eye is two times of FFA, and astigmatism aberration equivalent to two times of FFA occur. Conclusions: The critical problem when wearing sport sunglasses is astigmatism due to large FFA of sunglasses frame. The aberration problem of lens can be resolved by prescription of toric lens, but toric lens also have adaptation problem and also can not resolve the problem of aberration difference between left and right lens when viewed sideways. These optical problem of sport sunglasses can be solved only by frame of small FFA such as clip-in sunglasses frame.
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KEYWORD
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Sports sunglasses, FFA, Astigmatism, Aberration
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