Analysis of the ESCRS calculator's prediction accuracy

Purpose:To evaluate prediction accuracy of formulas included in the ESCRS online intraocular lens (IOL) calculator using standard keratometry (K) or total keratometry (TK).Setting:Hospital-based academic practice.Design:Retrospective case-series.Methods:523 patients with cataract (523 eyes) were included in this study. The outcome measures were trimmed means of the spherical equivalent prediction error (SEQ-PE, trueness), precision and absolute SEQ-PE (accuracy) of all 7 formulas available on the ESCRS online IOL calculator, as well as mean (Mean-All) and median (Median-All) of the predicted SEQ refraction of all formulas. Subgroup analyses evaluated the effect of axial length on formula accuracy.Results:Trimmed-mean SEQ-PE range of all formulas varied from -0.075 to +0.071 diopters (D) for K-based and from -0.003 to +0.147 D for TK-based calculations, with TK-based being more hyperopic in all formulas (P <.001). Precision ranged from 0.210 to 0.244 D for both K-based and TK-based calculations. Absolute SEQ-PE ranged from 0.211 to 0.239 D for K-based and from 0.218 to 0.255 D for TK-based calculations. All formulas, including Mean-All and Median-All, showed high accuracy, with 84% to 90% of eyes having SEQ-PEs within 0.50 D.Myopic trimmed-mean SEQ-PEs significantly different from zero were observed in long eyes for Pearl DGS (-0.110 D, P =.005), Hill RBF (-0.120 D, P <.001), and Hoffer QST (-0.143 D, P =.001) and in short eyes for EVO 2.0 (-0.252 D, P =.001), Kane (-0.264 D, P =.001), Hoffer QST (-0.302 D, P <.001), Mean-All (-0.122 D, P =.038), and Median-All (-0.125 D, P =.043).Conclusions:Prediction accuracy of all ESCRS IOL calculator formulas was high and globally comparable. TK-based calculations did not increase prediction accuracy and tended toward hyperopia. Observations indicating formula superiority in long and short eyes merit further evaluation.