Comparison of IOL power calculation formulas in short eyes using ESCRS calculator and eyetemis: Influence of anterior segment biometry

This study compared the refractive prediction accuracy of seven contemporary intraocular lens (IOL) power calculation formulas in eyes with short axial length and assessed the influence of anterior chamber depth (ACD) and lens thickness (LT) on prediction error (PE). A total of 124 eyes with an axial length ≤22.0 mm that underwent uncomplicated phacoemulsification with implantation of a Tecnis ZCB00 IOL were included. Predicted postoperative refractions were obtained using the ESCRS calculator for Barrett Universal II, Cooke K6, EVO 2.0, Hill-RBF 3.0, Hoffer QST, Kane, and Pearl-DGS. Formula performance was evaluated using robust trimmed-mean analyses of trueness, precision, and accuracy implemented in the Eyetemis platform, along with conventional PE metrics and the proportions of eyes within predefined error thresholds. The mean axial length was 21.67 ± 0.31 mm, and the mean implanted IOL power was 25.2 ± 1.6 D. Kane showed a lower trimmed-mean absolute PE than Hoffer QST (0.376 vs. 0.445 D; p = 0.014). No significant inter-formula differences were observed at clinically relevant error thresholds. ACD and LT showed weak, formula-specific associations with PE; however, these findings were exploratory and not clinically actionable. Overall, contemporary formulas provided broadly comparable refractive accuracy in short eyes, although small formula-specific differences were observed.