IOL Constant Optimization

Differences between IOL designs and biometry methods are sources of systematic error and can displace the average prediction error away from 0.0D. These require an adjustment of the IOL constant to reset the mean prediction error to 0.0D0.0D, so that the IOL formula can perform at its best. This review discusses the reasons why IOL constants may differ based on IOL characteristics and biometry method, as well as causes of erroneous estimation of IOL constants that should be taken into account. The chapter also describes various methodologies for optimizing IOL constants, from simple empirical methods to the conventional optimization approach by iteration using computerized spreadsheets. The code to perform these calculations is provided. The chapter ends by discussing the IOL power formulae with more than one constant and how these can be optimized.