SRK II formula in the calculation of intraocular lens power

We studied 400 eyes which underwent cataract extraction with posterior chamber intraocular lens (IOL) implantation to compare the predictive accuracy of various IOL power calculation formulae. The new Sanders-Retzlaff-Kraff (SRK) II formula was more accurate than the original SRK and Binkhorst II formulae. Modification of the A constants used in the SRK II formula to make it 'surgeon specific' improved its performance further; 80% of the eyes had less than 1 dioptre error and only one eye (0.3%) had an error of more than 3 dioptres.