Modified double-K method for intraocular lens power calculation after excimer laser corneal refractive surgery

Purpose: To propose the new anterior-posterior method (A-P method) that does not require historical data to calculate intraocular lens (IOL) power after laser in situ keratomileusis (LASIK) and to compare the accuracy of the method with other IOL formulas after LASIK. Setting: Keio University Hospital, Tokyo, Japan. Design: Case series. Methods: Eyes having phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. The A-P method is a modification of the double-K method using the SRK/T formula in which the estimated pre-LASIK keratometry (K) power calculated from the post-LASIK posterior sagittal power in the 6.0 mm zone is used for the preoperative K value in the double-K method and the post-LASIK anterior sagittal power is used for the postoperative K value. The accuracy of the A-P method was compared with that of other formulas that do not require preoperative data and with formulas that require preoperative data. Results: The median values of the arithmetic and absolute prediction errors using the A-P method were 0.16 diopter (D) and 0.54 D, respectively. The prediction errors using the A-P method were within ±0.50 D in 46.4% of eyes and within ±1.00 D in 75.0%. The percentage of eyes within ±1.00 D of the prediction errors with the A-P method was highest with the no-history methods. Conclusion: The A-P method may be a good option for calculating IOL power in eyes having cataract surgery after LASIK when preoperative LASIK data are unavailable. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.