A new centralperipheral corneal curvature method for intraocular lens power calculation after excimer laser refractive surgery

. Purpose: To propose the centralperipheral (C-P) method, which requires no data history to calculate intraocular lens (IOL) powers for eyes that underwent laser in situ keratomileusis (LASIK), and compare the accuracy of the C-P method with other IOL formulas for eyes after LASIK. Methods: Sixteen patients with cataract (25 eyes) who underwent myopic LASIK were analysed retrospectively. The C-P method is a modified double-K method using the SRK/T formula, in which the estimated pre-LASIK keratometric power calculated from the post-LASIK peripheral anterior sagittal power (also called the axial power) is used for the Kpre in the double-K method using the SRK/T formula, and the post-LASIK anterior sagittal power is used for the Kpost. We compared the accuracy of the C-P method with other popular IOL calculation formulas for use in eyes after LASIK. Results: The median values of the arithmetic and absolute prediction errors with the C-P method were 0.11diopter (D) (range, 1.67 to 1.97D) and 0.55D (range, 0.021.97D), respectively. The prediction error using the C-P method was within +/- 0.5D in 48% of eyes, within 1.0 to +0.5D in 60% of eyes, and within +/- 1.0D in 68% of eyes. The C-P method resulted in a significantly higher percentage of eyes within +/- 0.5D than the BESSt formula, Shammas-PL formula, true net power method, double-K method using 43.5D for Kpre, and Feiz-Mannis method. Conclusion: The C-P method may be a good option for calculating IOL powers in eyes undergoing cataract surgery after LASIK when the preoperative LASIK data are unavailable.