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Which formula works best for IOL calculation?

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Session Details

Session Title: Cataract Surgery Outcomes. IOL Power Calculations

Session Date/Time: Monday 07/09/2015 | 16:30-18:30

Paper Time: 16:42

Venue: Room 1

First Author: : W.Haigis GERMANY

Co Author(s): :                        

Abstract Details


From literature, it is not evident which algorithm to determine IOL power has the best performance. It seems as if for some lenses a given formula is more suitable than for other lenses. The purpose of this study is to derive methods which allow different IOL power formulas to be compared in a fair, objective and scientifically proper manner.


Department of Ophthalmology,University of Wuerzburg,Germany


For 15 popular IOLs and the classical IOL formulas (Haigis, Holladay-1, Hoffer Q, SRK/T, SRK2), the refractive outcomes were analyzed.Optimized lens constants had been derived for all IOLs based on a high number (n=585…5363) of individual clinical results. For all IOLs and all formulas, the following characteristics were determined: mean arithmetic prediction error, standard deviation of the mean error, median absolute prediction error, slope of the prediction error vs axial length, percentage of correct refraction predictions within ± 1.0 D.


The proper combination of the above statistical characteristics allows the definition of an error function which is to be minimized for best performance. Surprisingly, there is no IOL power formula which performs best for all IOLs. The Haigis formula with all 3 constants optimized has the highest performance index in 80% of all cases, followed by the Holladay-1 formula in 13% of all cases and the SRK/T and the Haigis formula with single optimization (each in 7%).


While there seems to be no algorithm which works best for all IOLs, the Haigis formula with triple optimization has the highest performance index (smallest error sum) in 80% of all cases.

Financial Interest:

One of the authors gains financially from product or procedure presented

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