IOL Calculations Following Keratorefractive Surgery

lation remains a challenge for lens surgery in eyes that have undergone previous keratorefractive surgery. There are two key issues: (1) The estimation of effective lens position (ELP) by the thirdor fourth-generation formulas is not correct when the postoperative corneal power values are used [1, 2]; and (2). In a post-surgical cornea, the standard keratometry or computerized videokeratography (CVK) may not accurately measure the corneal curvature, and the calculation of corneal power from the anterior corneal measurement by using the standard effective refractive index of the cornea (1.3375) is not appropriate in eyes following procedures that remove corneal tissue (e.g., excimer laser photorefractive keratectomy [PRK] or laserassisted in-situ keratomileusis [LASIK]).