Ray tracing software for intraocular lens power calculation after corneal excimer laser surgery

To evaluate the accuracy of intraocular lens (IOL) power calculations using ray tracing software in eyes after myopic laser in situ keratomileusis (LASIK).

Twenty-four eyes of 17 cataract patients who underwent phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. The IOL power calculation was performed using OKULIX ray tracing software. The axial length was measured using the IOLMaster and keratometry data using TMS2N. The accuracy of the IOL power calculation using OKULIX was compared with those using the Camellin-Calossi, Shammas-PL, Haigis-L formulas and the double-K SRK/T formula using 43.5 diopters (D) for the Kpre.

The mean values of the arithmetic and absolute prediction errors were 0.63 ± 0.85 and 0.80 ± 0.68 D, respectively. The arithmetic prediction error by OKULIX was a significant hyperopic shift of the distribution of the postoperative refractive errors compared to the Camellin-Calossi, Shammas-PL and Haigis-L formulas (P < 0.05), and the absolute prediction error showed no significant difference with other formulas. The prediction errors using OKULIX were within ± 0.5 D in 10 eyes (41.7 %) and within ± 1.0 D in 18 eyes (75.0 %). The percentages of eyes within ± 1.0 D using OKULIX were comparable to those obtained using the Camellin-Calossi, the Shammas-PL formulas and the double-K SRK/T formula using 43.5 D for the Kpre, and significantly (P < 0.05) higher than that obtained using the Haigis-L formula.

IOL power calculations using OKULIX provided predictable outcomes in eyes that had undergone a previous myopic LASIK.