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New intraocular lens power calculating formula by paraxial ray tracing

Poster Details

First Author: K.Ohnuma JAPAN

Co Author(s):    H. Juri   S. Goto   N. Maeda   T. Noda           

Abstract Details


OKULIX that is the latest intraocular lens (IOL) power calculation methods uses the ray tracing with consideration of spherical aberration and the formula of predicting anterior chamber depth (ACD) from axial length and the others parameters. And it is known that OKULIX includes the term for compensating total error. We believe that the IOL power prediction method using the paraxial ray tracing is useful in the case of precious ACD. Here, the purpose is to construct a new power prediction method using the paraxial ray tracing and to compare the precision with OKULIX.


Surgery and data acquisition: Tokyo medical center Tokyo Japan, data analysis: University laboratory Center for Frontier Medical Engineering Chiba University Chiba Japan


A new formula of calculating IOL power by using the paraxial ray tracing is established by using radii of an anterior surface of cornea and the posterior, the ACD, the axial length, and thickness of an intraocular lens. The predictive powers are compared with the inserted IOLs. In addition, the comparison with the predictive powers by OKULIX is performed. in the cases that the difference between the predicting ACD by OKULIX and ACD after operation was less than 0.2mm. The data used here were 17 eyes with W-60○R (Santen) and 32 eyes with Acrysof Toric○R (Alchon).


The new formula named JOTING was established by using the solution of the quadratic equation. In W-60, JOTING had the mean error 0.06(D) and the standard deviation 0.982(D). The mean error -1.15(D) and the standard deviation 0.843(D) were obtained by OKULIX. In Acrysof, JOTING had the mean error -0.75[D] and the standard deviation 0.793. The mean error -1.26(D) and the standard deviation 0.851(D) were obtained by OKULIX. It is found that JOTING has higher precision than OKULIX from the above-mentioned result about Acrysof. In addition, in the case of W-60, the values of the standard deviation ware nearly same.


The new formula JOTING that uses the paraxial ray tracing has the better precision than OKULIX. This seems to show that IOL power calculation does not need the consideration of spherical aberration.

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