A Comparison of Intraocular Lens Power Calculation Formulas in High Myopia

PURPOSE: To comparatively evaluate the accuracy of newer intraocular lens (IOL) calculation formulas and common third-generation formulas after Wang-Koch adjustment in the prediction of postoperative refraction in highly myopic eyes. METHODS: This was a retrospective study including eyes with high myopia that had uncomplicated cataract surgery with implantation of an AcrySof MA60MA IOL (power range: -5.00 to +5.00 diopters [D]) (Alcon Laboratories, Inc). All patients underwent optical biometry ( Carl Zeiss IOLMaster 500 and IOLMaster 700, and Allegro Biograph) and the postoperative spherical equivalent for the implanted IOL was estimated using SRK/T, Holladay 1 ( both Wang-Koch adjusted), Haigis, Barrett Universal II, Kane, Ladas, and Hill-RBF v2.0 formulas. Outcomes included the median absolute prediction error (MedAE) and the proportion of eyes within +/- 0.25, +/- 0.50, and +/- 1.00 D of the preoperative prediction. RESULTS: Eighty-two eyes with a mean axial length of 30.89 +/- 1.85 mm were included. The MedAE in ascending order was Hill-RBF v2.0 0.31 D, Kane 0.33 D, Barrett 0.36 D, Holladay I wk 0.37 D, SRK/T wk 0.37 D, Holladay I wk 0.43 D, Haigis ULIB 0.54 D, and Ladas 0.61 D. The formula with the lowest MedAE (Hill-RBF v2.0) yielded a prediction error within +/- 0.25, +/- 0.50, and +/- 1.00 D in 43.1%, 70.6%, and 94.1% of cases, respectively. CONCLUSIONS: Recent formulas such as Barrett Universal II, Kane, and Hill-RBF v2.0 and Wang-Koch adjusted formulas perform well in this subset of patients with high myopia. The Hill-RBF v2.0 formula had the lowest MedAE and highest proportion of eyes within +/- 0.25, +/- 0.50, and +/- 1.00 D of the predicted target.