A method of calculating the required power of an intraocular lens to be implanted in an eye having the steps of measuring the axial length, preoperative anterior chamber depth and natural lens thickness of the eye, measuring and averaging corneal radii of curvature along a first axis and along a second axis normal to the first axis, calculating a lens locator constant from the axial length and the averaged corneal radii of curvature using a quadratic surface equation, determining a postoperative anterior chamber depth using the measured preoperative anterior chamber depth, the measured natural lens thickness and the calculated constant and calculating the required power of the intraocular lens and the predicted postoperative refraction using the postoperative anterior chamber depth.