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KMID : 1011420200250040395
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Journal of Korean Ophthalmic Optics Society
2020 Volume.25 No. 4 p.395 ~ p.403
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Change in Lateral Phoria under a Phoropter and Trial Frame in Phoria Tests
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Oh Kwang-Keun
Cho Hyun-Gug
Moon Byeong-Yeon
Kim Sang-Yeob
Yu Dong-Sik
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Abstract
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Purpose: To evaluate the lateral phoria from several clinical phoria tests using a phoropter and trial frame.
Methods: Sixtyeight patients (mean age 23.01±1.81 years old) underwent a subjective refraction and lateral phoria test using four clinical phoria tests such as the von Graefe test, the Howell phoria card test, the Maddox rod test, and the alternating cover test under two conditions of phoropter and trial frame. In addition, by classifying the type of phoria and subjects who need to consider prism prescription, and the difference in lateral phoria between the two conditions was compared.
Results: When the two conditions were compared, a significant reduction was found in the mean lateral phoria in the lateral phoria tests at near and distance using trial frames. In addition, the exophoria group (exophoria greater than normal range) showed a larger mean difference than the orthophoria group (exophoria within normal range). In the group that considered prism correction, only the von Graefe test and the Howell phoria card test showed significant differences.
Conclusions: The amount of lateral phoria measured in various lateral phoria tests was smaller when the trial frame was used. Therefore, it is desirable to use a trial frame similar to free space when performing the lateral phoria test considering the prism prescription.
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KEYWORD
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Lateral phoria, Free space, Phoropter, Trial frame, Mechanical space
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