Accuracy of Intraocular Lens Power Calculation Formulas for Two Single-Piece Acrylic IOL Models in Eyes with a Shallow Anterior Chamber

Abstract

Introduction: This study evaluated whether the refractive prediction accuracy of conventional and new-generation intraocular lens (IOL) power calculation formulas differs between two single-piece acrylic IOL models in eyes with a shallow anterior chamber depth (ACD). Methods: In total, 100 eyes implanted with Softec HD IOLs (Lenstec) and 102 eyes implanted with SN60WF IOLs (Alcon) were included. All eyes had an ACD of ≤3.0 mm. The prediction error (PE) and mean absolute error (MAE) of 11 formulas, with and without optimized constants, were evaluated, including seven new-generation formulas (Barrett Universal II [BUII], Cooke K6 [K6], EVO 2.0, Hill-RBF 3.0, Hoffer QST, Kane, and Pearl-DGS) and four conventional formulas (Haigis, Hoffer Q, Holladay 1, and SRK/T). Results: The new-generation formulas (except K6) showed myopic PEs ranging from −0.108 to −0.181 D in the Softec group; most of these formulas (except Pearl-DGS and Hoffer QST) showed hyperopic PEs ranging from 0.120 to 0.310 D in the SN60WF group. Both before and after optimization, Hill-RBF 3.0 and Pearl-DGS yielded the lowest MAEs in the Softec and SN60WF groups, respectively. Before optimization, most formulas had MAEs > 0.43 D in the Softec group and <0.38 D in the SN60WF group; after optimization, the MAEs were 0.408–0.479 D and 0.334–0.377 D, respectively. Conclusions: The new-generation formulas with ULIB constants showed myopic and hyperopic PEs in the Softec and SN60WF groups, respectively. The SN60WF IOL model demonstrated better refractive prediction accuracy than the Softec model. Formula selection according to IOL model may help improve refractive outcomes in eyes with shallow ACDs.