Ray Tracing For Intraocular Lens Calculation After Corneal Excimer Laser Surgery

Abstract

 

Purpose:

 

To evaluate the accuracy of the intraocular lens (IOL) power calculation using ray tracing software in eyes undergoing cataract surgery after myopic laser in situ keratomileusis (LASIK) and to compare the final refractive results with previously published formulas.

 

Methods:

 

Twenty-three eyes of 16 patients who had undergone phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. IOL power calculation was performed using a ray tracing software, OKULIX^® (Tomey Corp., Nagoya, Japan) with axial length measured by IOLMaster (Carl Zeiss, Jena, Germany) and keratometry data using TMS2N (Tomey). The prediction error was defined as the subtraction of the target refraction calculated by OKULIX^® from the actual postoperative subjective refraction (spherical equivalent) on the spectacle plane. The accuracy of the IOL power calculation using OKULIX^® was compared with those using the Haigis-L, the Camellin-Calossi, the Shammas-PL formulas, not requiring preoperative data.

 

Results:

 

The mean arithmetic and absolute prediction errors and the percentages of eyes within ±0.5 D and ±1.0 D were shown in Tables 1 and 2. There was no significant difference between OKULIX^® and other methods either in the mean absolute prediction error, or in the percentages of eyes within ±0.5 D. The percentages of eyes within ±1.0 D using OKULIX^® was significantly higher than those using Haigis-L formula (P = 0.036).

 

Conclusions:

 

OKULIX^® with TMS 2N topography data allowed a predictable outcome of IOL power calculation in eyes which underwent LASIK for myopia.  

 

 

Keywords: intraocular lens • refractive surgery • clinical (human) or epidemiologic studies: outcomes/complications