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KMID : 1011420120170020127
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Journal of Korean Ophthalmic Optics Society
2012 Volume.17 No. 2 p.127 ~ p.133
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The Study about Measuring Method in Radius of Eyeglasses Lens Curvature by using Keratometer
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Cha Jung-Won
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Abstract
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Purpose: The aim of this study is to investigate the measuring method in radius of eyeglasses lens curvature by
using keratometer in noncontact method.
Methods: A trial lens for vision test in diopter range from ?9.00 D to ?11.50 D were attached in front part of keratometer, after that we set eyeglasses lens at the place where eyeglasses lens is apart about 25 cm from front position of keratometer. We measured the radius of curvature from observation of clear mire image while the position of eyeglasses lens is changed in a small quantity. After that, we made some formulas for compensation of radius of curvature by using spherometer.
Results: The radius of curvature was successfully measured by keratometer with trial lens in front part of it. The measured radius of curvature was changed to compensation value using spherometer data, and the 5 kind of linear equation to make compensation value was made. Any kind of lenses measured by using keratometer that trial lens was attached in front part of it, after that it was confirmed that the result of calculation from line equation is exact in error ratio
below 3.5%.
Conclusions: It was confirmed that radius of eyeglasses lens curvature can be measured by using keratometer by noncontact method, and the accuracy is higher than “lens measure”.
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KEYWORD
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Keratometer, Eyeglasses lens, Radius of curvature, Compensation equation, Noncontact method
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