Comparing the Accuracy of Four Intraocular Lens Formulas in Eyes with Two Types of Widely Used Monofocal Lens Implants

Abstract

The present study aimed to compare the accuracy of intraocular lens calculation formulas Barrett Universal II, Hoffer Q, Holladay 1, and SRK/T in the prediction of postoperative refraction for two widely used monofocal implants: SN60WF and ZCB00. All eyes were divided based on axial length (<22 mm, 22–24.5 mm, and >24.5 mm) and lens type. The mean and median of the absolute refractive error (AE) were calculated for all four formulas, using manufacturer-recommended lens constants as well as optimized constants. The subgroup analysis showed that the Barrett Universal II formula had the smallest mean absolute error in three groups (with short, medium, and long axial length) before and after lens factor optimization, and Holladay 1 had the best results in two groups (of medium and long axial length), and SRK/T in one short axial length group, as well as one medium AL group after A-constant optimization. This study hints at the versatility of the Barrett Universal II formula, a fourth-generation formula that is now widely available on most optical biometers and provides a useful tool of calculation for eyes of all axial lengths even without lens constant optimization.