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Evaluation of the Koch-Wang optimization method of axial length for intraocular lens power calculation in Myopic eyes

Poster Details

First Author: A.Atalla EGYPT

Co Author(s):    M. El-Agha   A. Osman   M. Osama        

Abstract Details


To evaluate the accuracy of intraocular lens (IOL) power calculation in myopic eyes using the axial length (AL) measured by optical biometry versus an optimized AL calculated by the Koch-Wang method.


Ophthalmology Department, Kasr El-Aini School of Medicine, Cairo University, and Ophthalmic Diagnostic and Laser Unit, Cairo University Hospitals, both in Cairo, Egypt.


A prospective study of 30 eyes of 23 patients with ALs greater than 25.0 mm that underwent phacoemulsification with IOL implantation in the capsular bag. The LENSTAR was used for preoperative IOL power calculation using the Holladay 1 formula and the LENSTAR AL (group 1), and for back-calculation of the prediction error (PE) for the same 30 eyes using the Holladay 1 formula and the optimized AL (group 2). IOL powers were selected based on the LENSTAR AL. The same IOL model was used in all eyes. Postoperative PEs and mean absolute errors (MAEs) were calculated one month after surgery.


The mean LENSTAR AL was 27.32 ±1.89 mm, and the mean optimized AL was 26.94 ±1.66 mm. The mean PE was +0.24 ± 0.54 D and -0.41 ± 0.54 D in groups 1 and 2 respectively (p=0.57), while the MAEs were 0.46 ± 0.36 D and 0.54 ± 0.39 D respectively (p=0.40). The postoperative spherical equivalent was within ±1.00 D of predicted in 86.7% and 90.0% of eyes respectively (p=0.47). However, 66.7% of eyes had a hyperopic outcome in group 1, in comparison to 20.0% that would be left hyperopic in group 2, although this was not statistically significant (p=0.26).


The Koch-Wang method of optimizing the AL would have reduced the percentage of eyes rendered hyperopic using the LENSTAR AL from 66.7% to 20.0%. Although this difference was not statistically significant, it represents a clinically significant improvement in IOL power prediction in these eyes. FINANCIAL DISCLOUSRE: NONE

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