Emmetropia Verifying Optical (EVO) formula in secondary scleral fixation using the Yamane technique: a retrospective comparison of intraocular lens power calculation formulas

To compare the accuracy of Emmetropia Verifying Optical (EVO) 2.0 with Sanders-Retzlaff-Kraff/Theoretical (SRK/T), Hoffer Q and Barrett Universal II (BUII) intraocular lens power calculation formulas in eyes that have undergone scleral fixation in Yamane technique. In this retrospective study, patients undergoing secondary intraocular lens fixation in Yamane technique between 03/2019 - 04/2024 were included. Prediction errors for EVO 2.0, BUII, SRK/T, and Hoffer Q formulas were calculated by subtracting the actual spherical equivalent from the predicted spherical equivalent. The performance of each method was evaluated by Eyetemis, an online tool for analyzing prediction errors. The tool includes robust t-tests to compare the trimmed means of the data. 59 eyes met the inclusion criteria and were included in the analysis. All formulas showed myopic mean refractive prediction errors. With regard to spherical equivalent prediction error (SEQ-PE), precision of the SEQ-PE and absolute SEQ-PE, there were no significant differences between the formulas examined. The EVO 2.0 formula showed the lowest trimmed mean error with 0.62±0.58 D followed by BUII with 0.66±0.71 D. Within ± 0.50 D the EVO 2.0 formula achieved the highest accuracy with 54% whereas BUII and Hoffer Q achieved the highest accuracy within ±0.25 D with 28%. The EVO 2.0 formula represents a viable option for IOL calculation in patients undergoing scleral fixation with the Yamane technique. Although none of the formulas showed significant differences in performance, all consistently resulted in a myopic prediction error in the analyzed cohort. Therefore, when using the Yamane technique, targeting a slightly hyperopic refraction may help compensate for this myopic shift in similar patient populations.