Comparison of Accuracy of Intraocular Lens Power calculation for Eyes with an Axial Length Greater Than 29.0 mm

Abstract

PurposeTo evaluate and compare the accuracy of six different formulas (EVO 2.0, Kane, SRK/T, Barrett Universal II, Haigis and Olsen) in intraocular lens (IOL) power calculation for extremely long eyes.MethodsRetrospective case-series. 73 eyes with axial length (AL) ≥ 29.0 mm and 920H IOL implantation were included. Prediction errors (PE) were calculated and compared between different formulas. Multiple regression analysis was performed to investigate factors associated with the PE.ResultsThe Kane formula had mean prediction error close to zero (-0.01 D, P = 0.841), whereas the EVO 2.0, SRK/T, Barrett Universal II, Haigis and Olsen formulas produced hyperopic outcomes (all P < 0.001). The median absolute error produced by the EVO 2.0, Kane, Barrett Universal II and Olsen formulas showed no significant difference (0.33 D, 0.30 D, 0.29 D, 0.34 D, respectively, pairwise comparison P > 0.05), but was significantly lower than that of the SRK/T and Haigis formulas (0.85 D, 0.80 D, respectively, pairwise comparison P＜ 0.001). The accuracy of the SRK/T formula in extremely myopic eyes was affected by the AL, suggesting that a longer AL was always associated with a hyperopic surprise and a shorter AL was always associated with a myopic surprise, whereas the accuracy of other formulas was less affected by the AL.ConclusionsFor cataract patients with axial length greater than 29.0 mm, the accuracy of the EVO 2.0, Kane, Barrett Universal II and Olsen formulas is comparable and significantly better than that of the SRK/T and Haigis formulas.