ESCRS - POCAT633 - Comparative Accuracy Of Multiple Intraocular Lens Power Calculation Formulas In Eyes With Previous Ray-Tracing–Guided Lasik

Comparative Accuracy Of Multiple Intraocular Lens Power Calculation Formulas In Eyes With Previous Ray-Tracing–Guided Lasik

Published 2026 - 44th Congress of the ESCRS

Reference: POCAT633 | Type: Free paper | DOI: 10.82333/n0an-er20

Authors: Dr Xueyan Zhou* ¹ , Dr Xia Hua ¹ , Dr Bo Yuan ¹

¹Aier Eye Institute,Changsha,China

Purpose

To evaluate the theoretical predictive accuracy of multiple contemporary intraocular lens (IOL) power calculation formulas in eyes with previous ray-tracing–guided LASIK, and to assess the relative performance of keratometry (K) versus total keratometry (TK)–based calculations in this post-keratorefractive population.

Setting

The study included 40 eyes of 20 patients who underwent ray-tracing–guided LASIK at Tianjin University Aier Eye Hospital between September 2025 and March 2026. Using a theoretical surgical model, five IOL power calculation formulas (Barrett True-K, EVO 2.0, Hoffer QST, Kane, and Pearl-DGS) were applied to estimate postoperative refractive outcomes. IOL power was calculated using both K and TK values, and results were compared with preoperative Barrett Universal II (BUII)–based calculations.

Methods

Comprehensive biometric evaluations were performed pre- and postoperatively using the IOLMaster 700, including axial length and corneal measurements, together with manifest refraction. Prediction error (PE) was defined as the difference between the manifest refraction–derived spherical equivalent and the formula-predicted value, and absolute error (AE) as the absolute value of PE. The study compared PE, mean absolute error (MAE), median absolute error (MedAE), and the proportions of eyes within ±0.25 D, ±0.50 D, ±0.75 D, ±1.00 D, and ±2.00 D.

Results

The superior performing formulas were EVO 2.0 (K) (MAE 0.29 D, MedAE 0.20 D), Barrett True-K (K) (MAE 0.30 D, MedAE 0.25 D), and Pearl-DGS (MAE 0.35 D, MedAE 0.26 D). EVO 2.0 (K) and Barrett True-K (K) achieved the lowest prediction errors, with 82.4% and 79.4% of eyes within ±0.50 D, and 97.1% and 100% within ±1.00 D, respectively. Pearl-DGS also demonstrated favorable accuracy (70.6% within ±0.50 D; 97.1% within ±1.00 D). Kane (TK), Barrett True-K (TK), EVO 2.0 (TK), and Hoffer QST (K) showed moderate predictive performance, whereas Hoffer QST (TK) and Kane (K) were associated with higher prediction errors. Differences among formulas were statistically significant (Friedman χ² = 97.70, p < 0.001).

Conclusions

EVO 2.0 (K), Barrett True-K (K), and Pearl-DGS demonstrated superior predictive accuracy for IOL power calculation in eyes after ray-tracing–guided LASIK. Among them, EVO 2.0 (K) yielded the lowest refractive prediction errors and the highest proportions of eyes within ±0.50 D and ±1.00 D. Contemporary formula selection remains critical in post-keratorefractive eyes. Further large-scale and externally validated studies are warranted.