KMID : 0360220090500121795
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Journal of the Korean Ophthalmological Society 2009 Volume.50 No. 12 p.1795 ~ p.1799
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Comparative Analysis of Contact and Immersion Technique in Ultrasonographic Biometry
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Rhim Jay-Won
Kang Su-Yeon Kim Hyo-Myung
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Abstract
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Purpose: To establish the accuracy of the newly released biometer Ocuscan RxP¨Þ (Alcon, USA) by comparison with the established Ultrasonic Biometer Model 820¨Þ (Allergan Humphrey, USA), and to compare the accuracy of contact and immersion biometries.
Methods: This is a prospective study involving 27 patients (40 eyes) who were scheduled for cataract surgery and had axial lengths measured with an Ocuscan RxP¨Þ biometer using both contact (Method 1) and immersion (Method 2) techniques. As a reference, a contact type Ultrasonic biometer 820¨Þ (Method 3) was also used. IOL(Intraocular Lens) power for the cataract surgery was calculated using this result. An axial length which would have caused no post-operative refractive error was reversely calculated from the difference of target diopter and post-operative refractive error. This length was compared with the axial lengths obtained via Methods 1, 2 and 3.
Results: The means and standard deviations for the measurement sets were compared. Methods 1 and 2 showed no significant difference (23.22¡¾0.68, 23.24¡¾0.69 mm, p=0.55). The axial length measured by Method 3 was 23.32¡¾0.67 mm. The difference between the target refraction and post-operative refractive error was 0.29¡¾0.60D. The axial length was reversely calculated from the difference (23.07¡¾0.84 mm). The differences between the reversely calculated axial lengths and those of Methods 1, 2 and 3 were 0.15¡¾ 0.31, 0.17¡¾0.31 and 0.24¡¾0.28 mm, respectively.
Conclusions: Biometric results from Methods 1 and 2 caused less refractive error than did Method 3. The contact and immersion methods are both accurate for IOL power calculation if performed by a well-skilled examiner.
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KEYWORD
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Alcon Ocuscan, Axial length, Contact, Immersion, Ultrasonic biometry
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