Purpose.(1) To determine the effect of myopic and hyperopic laser in situ keratomileusis (LASIK) on calculation of intraocular lens (IOL) power. (2) To determine a standard way to approach the IOL power determination after LASIK, and (3) To compare different suggested methods.Methods.Biometric analysis and theoretical calculation of IOL powers for eyes undergoing LASIK for myopia and hyperopia were performed.Results.Manual keratometry after LASIK for myopia resulted in underestimation of IOL power. Manual keratometry after hyperopic LASIK resulted in overestimation of IOL power. The amount of error was directly related to the amount of correction by LASIK.Conclusion.The pre-LASIK refraction can be used theoretically to determine an accurate IOL power.