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. [ J Refract Surg . 2021;37(3):207–211.]