Comparison Of Formula Accuracy For Calculating Multifocal Intraocular Lens Power In Asian Patients

To evaluate the accuracy of newer formulas(Barrett Universal ll, EVO 2.0, Kane, Nallasamy, and PEARL-DGS) and the Haigis formula in Asian patients implanting Alcon TFNT multifocal intraocular lens(IOL). 

 Miracle Eye Clinic, Seoul, Korea.

A total of 3100 randomly selected eyes per patient underwent cataract surgery with Acrysof IQ TNFN IOL implantation based on a swept-source optical coherence tomography(SS-OCT) biometry results were reviewed. The standard deviation(SD) of prediction error was assessed for the whole group, and the non-parametric tests were used for the short and long axial length(AL) subgroup analysis. For further investigation, the Cooke-modified-Axial Length(CMAL) was experimentally applied to the Haigis formula. A modified AL, which translates into the conventional AL in its algorithm, was applied to the PEARL formula. The correlations between the Haigis, PEARL and other newer formulas were calculated to see the difference with AL modification. 

 

 

 The PEARL formula significantly outperformed others. Unlike the Haigis formula, all the newer formulas exhibited hyperopic outcomes in short eyes and clinically significant myopic results in long eyes. The application of CMAL to the Haigis formula with single constant optimization, roughly reflecting the newer formulas' working(AL modification, optical vergence formula, single constant), produced similar behaviour and higher correlation to the newer formulas. The PEARL formula displayed decreased myopic shifts in long eyes and a lower correlation to other newer formulas when the modified AL was applied. The CMAL-applied, triple-optimized Haigis formula yielded significantly improved accuracy, only second to the PEARL formula. 

The newer formulas performed excellently in this study. However, besides the PEARL formula, other newer formulas(Barrett Universal ll, EVO 2.0, Kane and Nallasamy) failed to reveal significant superiority over the Haigis formula, mainly due to their substantial myopic outcomes in the long AL subgroups. The AL modification algorithms employed in the newer formulas, to cope with the optical biometry's overestimation of the AL in the long eyes, seem to overcompensate, particularly in the Asian population's long eyes.