What question did this study set out to answer?

This research aims to compare the accuracy of IOL formulas in highly myopic eyes and identify key parameters affecting prediction error.

May 7, 2026

Intraocular lens power calculation in highly myopic eyes with axial length ≥ 28 mm: Impact of two corneal keratometries and anterior segment parameters

Key Points

This research aims to compare the accuracy of IOL formulas in highly myopic eyes and identify key parameters affecting prediction error.
Retrospective observational study of 415 eyes undergoing phacoemulsification with IOL implantation.
Evaluation of 12 IOL formulas including conventional and new-generation formulas.
Use of keratometry and total keratometry to predict postoperative spherical equivalent and measure anterior segment parameters.
Application of stepwise linear regression to identify parameters associated with prediction error.
EVO 2.0 formula showed highest accuracy among IOL formulas using keratometry.
Significant effect of lens thickness on prediction error, with greater thickness linked to myopic shifts.
Keratometry method outperformed total keratometry for most IOL formulas compared.

Abstract

PURPOSE: To compare the accuracy of 12 intraocular lens (IOL) formulas in eyes with axial length (AL) ≥ 28 mm and to identify the anterior segment parameters independently affecting prediction error (PE). METHODS: A total of 415 eyes undergoing phacoemulsification with IOL implantation at Shanghai General Hospital were included in this retrospective observational study. Refractive PEs were calculated for 5 conventional formulas (Haigis, Hoffer Q, Holladay 1, Holladay 2 and SRK/T) with optimization and 7 new-generation formulas (Barrett Universal II BUII, Cooke K6, EVO 2.0, Hoffer QST, Kane, Ladas Super Formula LSF and Pearl-DGS). Predicted postoperative spherical equivalent (SE) was calculated using keratometry (K) and total keratometry (TK) measured by IOLMaster 700. Q values, posterior mean keratometry, corneal volume, anterior chamber volume and angle and back-to-front corneal radius ratio were measured by Pentacam. Stepwise linear regression identified parameters associated with PE. RESULTS: Using the K method, BUII, EVO 2.0, Hoffer QST, Holladay 2, Kane and Pearl-DGS showed the lowest median absolute PE (MedAE = 0.32, 0.31, 0.32, 0.30, 0.30 and 0.32 D) and highest formula performance index (FPI = 0.74, 0.80, 0.69, 0.68, 0.60 and 0.69). BUII, Cooke K6, EVO 2.0, Holladay 2 and Pearl-DGS performed stably across axial groups (p > 0.05). K achieved lower AE than TK for all formulas (p < 0.05), except Hoffer QST (p = 0.497), Holladay 2 (p = 0.140) and Pearl-DGS (p = 0.912), with Kane performing better using TK (p = 0.024). Lens thickness (LT) independently affected PE for Holladay 2 and all new-generation formulas, with greater LT associated with myopic shifts (p < 0.05). CONCLUSIONS: EVO 2.0 formula provided the most accurate predictions with K method. Except for Kane, K outperformed TK. LT independently influences PE and should be considered in future IOL calculations.

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