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KMID : 1159320130150040339
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Korean Journal of Vision Science
2013 Volume.15 No. 4 p.339 ~ p.348
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Comparison on the Accuracy of Intraocular Lens Power Calculation Formulas according to Axial Length
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Choi In-Yong
Leem Hyun-Sung
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Abstract
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Purpose: To investigate accuracy of formulas and tendency of refractive errors by using comparison method according to the axial length between predictive refraction of five intraocular lens power calculation formula and errors of actual refraction after surgery.
Methods: Two cataract patient groups divided to measured axial length by applanation ultrasonography; groupⅠ was comprised of 64 people(91 eyes) whose long eyes were over 25mm, and groupⅡ was comprised of 75 people(112 eyes) whose normal eyes were 22mm-25mm. Cataract surgery have been done by the same surgeon. In addition, according to measured axial length of long eyes intraocular lens power calculation is decided by SRK/T formula for groupⅠ and SRK Ⅱ formula for groupⅡ. After two mouths of IOL power was calculated with the SRK II, SRK/T, Binkhorst, Holladay I, and Hoffer Q formulas. The differences between the predicted refraction and the actual refraction were compared and analyzed.
Results: The subjects who underwent cataract surgery were in the mean age of 66.74 ± 9.40 years and 64 patients(91 eyes) were in groupⅠ and 75 patients(112 eyes) were in groupⅡ. Generally, SRK/T was the most accurate in MNE and MAE, but SRK Ⅱ and Binkhorst formula had the lowest accuracy. Group Ⅰ showed more MNE and MAE in compared to group Ⅱ(p＜0.05). Correlation of the axial length of long eyes and MNE in every formula showed the tendency such as negative correlation of hyperopic conditions((r=-0.335, r=-0.495, r=-0.583, r=-0.498, r=-0.169).
Conclusions: The result of this study represents that when axial length were long, deciding intraocular lens power to make refractive power is the same as myopia is safe in order to prevent hyperopic conditions after surgery. If SRK/T formula is considered, deciding intraocular lens power is relatively accurate, and if SRK Ⅱ formula is considered, possible errors must be referred.
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KEYWORD
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Axial Length, Biometry, Intraocular Lens(IOL) Power Calculations Formulas, Mean numerical errors(MNE), Mean absolute errors(MAE)
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