Improving the predictability of intraocular lens power calculations.

We reviewed the intraocular lens power calculations on 512 posterior chamber lens implantations and determined four ways to reduce the estimated 5% incidence of large postoperative refractive "surprises" (greater than 2 diopters [D]): First, preoperatively identify those patients who have greater than a 1-D difference between the theoretical and linear regression formulas. Second, repeat axial length and corneal power measurements in these patients to eliminate random error. Third, develop an individualized theoretical formula that accounts for constant bias. Fourth, encourage manufacturers to improve instrumentation for measuring corneal power and axial length. We also examined the disparity between the linear regression formula and the curvilinear theoretical formula.