LAUSR

PURPOSE To compare the accuracy and precision of the new Hill-RBF version 2.0 (Hill-RBF 2) formula with other formulas (Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T) in predicting residual refractive error after phacoemulsification in high axial myopic eyes. DESIGN Retrospective case series. METHODS 127 eyes of 127 patients with axial length (AL) ≥ 26mm were included. The refractive prediction error (PE) was calculated as the difference between the postoperative refraction and the refraction predicted by each formula for the intraocular lens (IOL) power actually implanted. Standard deviation (SD) of PE, median absolute PE (MedAE), proportion of eyes within ±0.25 D, ±0.50 D, ±1.00 D of PE were compared. A generalized linear model was used to model the mean function and variance function of the PE (indicative of the accuracy and precision) with respect to biometric variables. RESULTS The MedAE and SD of Hill-RBF 2 were lower than that of Hoffer Q, Holladay 1, and SRK/T (p≤0.036), and were comparable to Barrett Universal II and Haigis (p≥0.077). Hill-RBF 2 had more eyes within ±0.25 D of the intended refraction (59.84%) compared to other formulas (p≤0.034) except Barrett Universal II (p=0.472). AL was associated with the mean function or variance function of the PE for all formulas except Hill-RBF 2. CONCLUSIONS In this study, the precision of Hill-RBF 2 is comparable to Barret Universal II and Haigis. Unlike the other 5 formulas, its dispersion and the accuracy of the refractive prediction is independent of the AL.