Can the accuracy of intraocular lens calculations be improved?

Regression analysis of data from 222 extracapsular cataract extractions was performed to determine if the accuracy of IOL prediction in cataract surgery can be improved. Polynomial and piecewise regression of large, medium, and short eyes were used to calculate new formulas for IOL prediction. The Taylor series representation of the theoretical lens power formula was calculated to determine what combination of the variables for IOL power prediction are reasonable to consider in constructing a polynomial regression model. The formulas calculated from the data in this study were compared with other published methods of IOL calculation. In this study, the difference between the postoperative refraction error and emmetropia was independent of the formula used. The exception was the modified Binkhorst formula, which caused greater error. Inclusion of higher order terms in the regression formula or piecewise regression did not reduce the postoperative refractive error.