Comparison of the Hoffer Q and SRK-II fomulas in IOL Power Calculation

ABSTRACT

Although most available IOL power calculation formulas perform accurately for eyes of average axial length, they have been shown to be inaccurate for eyes that have unusually short and long axial length. To compare the prediction accuracy of new Hoffer Q with SRK-II formula, we reviewed, retrospectively, a series of 225 ECCE with PCL implantation cases, including 106 Hoffer Q group and 119 SRK-II group, each of which was further divided into subgroups based on axial length. The Hoffer Q formula overestimated the refraction and resulted in more myopic shift and was less accurate than SRK-II in all length eyes, except short length eyes. In short length eyes, both formulas had similar mean error and mean absolute error but Hoffer Q formula was more accurate than the SRK-II in +/- 0.5D prediction proportion.