Accuracy of Intraocular Lens Power Calculation Based on Total Keratometry in Patients with Flat and Steep Corneas

center dot PURPOSE: To analyze the accuracy of the current in-traocular lens power calculation formulas using standard keratometry (K) and total keratometry (TK) data in pa-tients with fiat and steep corneas. center dot DESIGN: Retrospective consecutive cross-sectional study. center dot METHODS: An optical biometer with swept-source op-tical coherence tomography was used in this retrospective study. The standard deviation (SD), mean absolute error (MAE), median absolute error (MedAE), and the pro-portion of eyes with prediction error (PE) within +/- 0.25 diopter (D), +/- 0.5 D, +/- 0.75 D, and +/- 1.00 D were calcu-lated to evaluate the refractive outcomes of each formula. center dot RESULTS: A total of 231 eyes from 231 patients were included. In the entire study cohort, the Emmetropia Verifying Optical (EVO) formula using TK data showed the lowest SD (0.383) and MAE (0.30) and the highest percentage of cases with a PE within +/- 0.5 D (81.4%). In the fiat keratometry group, the EVO ( P = .042), Haigis ( P = .043), Hoffer Q ( P = .038) and Holladay 1 ( P = .013) formulas using TK data had significantly lower SD than using K data. The EVO formula using TK data showed the lowest SD (0.357) and MAE (0.28). In the steep keratometry group, the Hoffer Q ( P = .036) and SRK/T ( P = .029) formulas using TK data had sig-nificantly lower SD than using K data. The BUII TK formula showed the lowest SD (0.431), MedAE (0.26), and MAE (0.32). center dot CONCLUSION: The TK data set showed a better trend of refractive outcomes, especially in the fiat and steep ker-atometry groups. EVO (TK) and BUII TK formulas were suggested for eyes with K values lower than 42 D and K values higher than 46 D, respectively. (Am J Ophthal-mol 2023;247: 103-110. (c) 2022 Elsevier Inc. All rights reserved.)