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KMID : 1159320070090010001
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Korean Journal of Vision Science
2007 Volume.9 No. 1 p.1 ~ p.16
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Comparison of Repeatability and Accuracy in Corneal Topographers
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Kim Jeong-Mee
Mah Ki-Choong
Ryu Dong-Kyu
Park Joon-Ho
Kim Young-Mi
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Abstract
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This study compared and analyzed the repeatability and the accuracy of four different corneal topographers which were clinically used. Using Orbscan IIz Slit-Scan System, Oculus Topography System, Eyesys Corneal Analysis System and Humphrey Atlas Corneal Topography System, the apical radius, simulated K-reading(flatter meridian/steeper meridian) of corneal central zones and eccentricity were measured respectively from both normal eyes. Repeatability was compared through two independent measurements by the same examiner and by another examiner respectively, from 47 subjects(94 eyes). Accuracy was measured through two independent measurements based on manual keratometry by the same examiner from 19 subjects(38 eyes). There were no significant differences in measurements by the same examiner, and there were no significant differences in measurements by another examiner, for any of the parameters tested for each topographer. The corneal topographers with the highest coefficient of repeatability (COR) were : Oculus(COR = 0.043) for apical radius, Eyesys(COR = 0.034) for flatter simulated K-reading, Oculus(COR = 0.048) for steeper simulated K-reading and Eyesys(COR = 0.024) for eccentricity. Oculus and Eyesys showed a bit more repeatability than Orbscan IIz and Humphrey Atlas in repeatability measurement parameters. Coefficients of accuracy based on manual keratometry were: 0.069, 0.075 for flatter K-reading and steeper K-reading respectively with Orbscan IIz, 0.047, 0.075 with Oculus, 0.047, 0.068 with Eyesys, and 0.066, 0.078 with Humphrey Atlas. The accuracy of flatter K-reading showed higher than steeper K-reading for all of 4 corneal topographers. Eyesys Corneal Analysis System showed higher in accuracy measurement parameters. The results of comparing the repeatability and the accuracy of four corneal topographers showed that there were no large differences among them.
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KEYWORD
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Corneal Topography System, Manual keratometry, Apical radius, Simulated K-reading, Eccentricity, Repeatability, Accuracy
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