Intraocular lens power calculation for planned ametropia: a clinical study.

A prospective series of 25 eyes received an intraocular lens (IOL) of power calculated for planned ametropia, by means of the formulae of R. D. Binkhorst, from data of axial length, corneal curvature, and postoperative anterior chamber depth. All the postoperative refractions were within the +/- 2 D range from the predicted refraction, confirming the clinical value of such calculation. A retrospective study of 100 eyes which had received a +19 D power Binkhorst IOL showed a wide range of change in refraction extending up to the +/- 6 D range, indicating that a 'standard' power IOL cannot be relied upon to reproduce the preoperative refraction. Calculation of IOL power from biometric data is essential when controlled postoperative ametropia is required.