Accuracy of newer intraocular lens power formulas in short and long eyes using sum-of-segments biometry.

PURPOSE:To analyze the accuracy of newer intraocular lens power formulas in long and short eyes measured using the sum-of-segments biometry. SETTING:Private practice, Lynwood, California. DESIGN:Retrospective observational study. METHODS:595 patients scheduled for cataract surgery had their eyes measured using the sum-of-segments biometry. The expected residual refractions were calculated using Barrett Universal II (B II), Barrett True Axial Length (BTAL), Emmetropia Verifying Optical (EVO), Hill-RBF, Hoffer QST, Holladay 2, Holladay 2-NLR, K6, Kane, Olsen, PEARL-DGS, T2, and VRF formulas and compared with the traditional Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. RESULTS:In the 102 long eyes, all new formulas had a mean absolute error (MAE) equal or lower than the traditional formulas, ranging from 0.29 to 0.32 diopter (D). In the 78 short eyes, BTAL, EVO, Hoffer QST, K6, Olsen, and PEARL-DGS formulas had the lowest MAE (0.33 D, 0.33 D, 0.31 D, 0.36 D, 0.32 D, and 0.32 D, respectively), whereas all traditional formulas exceeded 0.36 D. CONCLUSIONS:All new formulas performed equal or better than the traditional formulas with the sum-of-segments biometry. The best overall results in the short and long eyes as well as in the very short and very long eyes were noted with the BTAL, EVO, Hoffer QST, K6, Olsen, and PEARL-DGS formulas, closely followed by the B II and Kane formulas.