Accuracy of Intraocular Lens Power Calculation in Microspherophakia Patients: Comparison of 7 Formulas

Introduction: The purpose of this study was to compare the accuracy of seven formulas for intraocular lens power calculation in patients with microspherophakia (MSP). Methods: A retrospective case series included 44 eyes from 28 patients with MSP. The mean prediction error (PE) was calculated, and the accuracy was determined by formula performance index (FPI), median absolute error (MedAE), and percentage of eyes with a PE within ±0.25 diopters (D), ±0.50 D, ±0.75 D, and ±1.00 D. Depending on whether the patients had Marfan syndrome (MFS), MSP patients 36 were sub-divided into MFS and non-MFS group. Results: In the non-MFS subgroup, the performance of formulas ranked by FPI from highest to lowest was BUII, Emmetropia Verifying Optical (EVO), Kane, Haigis, Sanders-Retzlaff-Kraff/Theoretical (SRK/T), Holladay 1, and Hoffer Q. In the MFS subgroup, Kane achieved the best accuracy regarding the lowest MedAE and the largest percentage of PE in the range of ±0.50 D. Similar results were obtained in eyes with shallow anterior chamber depth (ACD). In the regular ACD subgroup, the EVO provided the highest prediction accuracy and SRK/T took the second place. In the deep ACD subgroup, Holladay 1 performed superiorly presenting the lowest standard deviation values, mean absolute error and MedAE. Conclusions: Overall, new generation formulas showed a better trend of refractive outcomes in MSP patients. The Holladay 1 formula was suggested for eyes with deep ACD, while Haigis was not recommended.