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KMID : 1159320160180040455
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Korean Journal of Vision Science
2016 Volume.18 No. 4 p.455 ~ p.463
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Accuracy of Axial Length Calculation Using Schematic Eyes in Ametropia
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Kim Hyeong-Su
Cho Hyun-Gug
Moon Byeong-Yeon
Yu Dong-Sik
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Abstract
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Purpose: To derive axial length(AL) calculation formulas for ametropia using measured corneal radius and spherical equivalent refractive error and to assess the accuracy of the formulas.
Methods: This study comprised 524 ametropic subjects(1048 eyes) with a mean age of 47.17±13.01 years. The formulas for calculation of ALs were obtained using Gullstrand’s exact schematic eye, Gullstrand’s simplified schematic eye, Gullstrand-Emsley’s schematic eye, Le Grand’s schematic eye, and Bennett and Rabbetts’ schematic eye, respectively. ALs were calculated from each formula by using measured corneal radius and spherical equivalent refractive error by auto-refractometer. The calculated ALs were compared with measured ALs by IOL-master, and the agreement between ALs were evaluated.
Results: The differences between measured AL and calculated AL of ametropia(myopic and hyperopic eyes) were small in the order of Gullstrand-Emsley’s schematic eye, Gullstrand’s simplified schematic eye, Bennett and Rabbetts’ schematic eye, Le Grand’s schematic eye, and Gullstrand’s exact schematic eye.
Conclusions: The accuracy calculation of axial length using the formula could be applied usefully to design of individual ophthalmic lenses.
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KEYWORD
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Axial length, Ametropia, Schematic eye, Refractive error, Corneal radius, Ophthalmic lens design
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