Comparison of the formula accuracy for calculating multifocal intraocular lens power: a single center retrospective study in Korean patients

Abstract

This study evaluated the accuracy of newer formulas (Barrett Universal II, EVO 2.0, Kane, Hoffer QST, and PEARL-DGS) and the Haigis formula in Korean patients with the Alcon TFNT multifocal intraocular lens. In total, 3100 randomly selected eyes of 3100 patients were retrospectively reviewed. After constant optimization, the standard deviation (SD) of the prediction error was assessed for the entire group, and the root mean square error was compared for short and long axial length (AL) subgroup analysis. The Cooke-modified AL (CMAL) was experimentally applied to the Haigis formula. All the newer formulas performed well, but they did not significantly outperform the Haigis formula. In addition, all the newer formulas exhibited significant myopic outcomes (- 0.23 to - 0.29 diopters) in long eyes. Application of the CMAL to the Haigis formula with single constant optimization produced similar behavior and higher correlation with the newer formulas. The CMAL-applied triple-optimized Haigis formula yielded a substantially smaller SD, even superior to the Barrett and Hoffer QST formulas. The AL modification algorithms such as the CMAL used in newer formulas to cope with optical biometry's overestimation of the AL in long eyes seemed to overcompensate, particularly in the long eyes of the East Asian population.

Figure 1

Mean prediction error plotted against the axial length groups of each formula. AL axial length, CMAL Cooke-modified axial length, D diopter, HSAL Haigis formula, single-optimized and AL-applied, HSCL Haigis formula, single-optimized and CMAL-applied, HTAL Haigis formula, triple-optimized and AL-applied, HTCL Haigis formula, triple-optimized and CMAL-applied, HQST Hoffer Q/Savini/Taroni formula, PEARL-rCMAL PEARL-DGS formula with reversed CMAL (= [AL + 0.05467 × lens thickness − 1.28353]/0.95855).

Figure 2

Percentage of absolute errors of each formula. AL axial length, CMAL Cooke-modified axial length, D diopter, HSAL Haigis formula, single-optimized and AL-applied, HSCL Haigis formula, single-optimized and CMAL-applied, HTAL Haigis formula, triple-optimized and AL-applied, HTCL Haigis formula, triple-optimized and CMAL-applied.