Accuracy of the ESCRS online calculator for enhanced monofocal intraocular lens power calculation

Purpose: To evaluate the refractive accuracy of the European Society of Cataract and Refractive Surgeons (ESCRS) online intraocular lens (IOL) calculator for enhanced monofocal IOLs and to compare its performance with commonly used IOL formulas, including BUII, SRK/T, and Haigis. Methods: This retrospective case-series included 95 eyes from 95 patients who underwent uneventful phacoemulsification with ICB00 IOL. IOL power was calculated using the ESCRS calculator (Cooke K6, EVO 2.0, Hill-RBF 3.0, Hoffer QST, Kane, and Pearl DGS), and BUII, SRK/T, and Haigis formulas using IOLMaster 700. Prediction error (PE), mean absolute error (MAE), median absolute error (MedAE), the proportion of eyes with a PE within ± 0.50 D of target refraction, and the formula performance index (FPI) were evaluated at 3 months postoperatively with and without constant optimization. Results: Without constant optimization, the Kane formula achieved the lowest MedAE (0.22 D) and the highest proportion of eyes with PE within ± 0.50 D (85.3%). With constant optimization, the Kane and Cooke K6 formulas showed the lowest MedAE (0.18 D each), and Kane and EVO 2.0 demonstrated the highest percentage of eyes within ± 0.50 D (85.3%). The proportion of eyes within ± 0.50 D showed statistically significant overall differences among formulas under both conditions (P < 0.05 each), although no significant pairwise differences were observed after optimization. The highest FPI values were observed for Cooke K6, Hill-RBF 3.0, and Kane, whereas SRK/T and Haigis consistently demonstrated the lowest performance. Conclusions: The ESCRS online IOL calculator demonstrated superior MedAE and FPI compared with traditional formulas (SRK/T and Haigis), while the accuracy in achieving a postoperative refraction within ±0.50 D was comparable among eyes implanted with enhanced monofocal IOLs. These results support the clinical utility of the ESCRS calculator for accurate and efficient IOL power calculation, regardless of constant optimization status.