Evaluation of the value of preoperatively determined IOL power.

We compared a group of 25 Pearce posterior chamber lens implants with a group of 10 Binkhorst iridocapsular lens implants. Two methods of pre-operative intra-ocular lens power determination were compared. A formula based on geometrical optics was used and a linear regression method. The pre-operatively calculated lens power was compared with the real implant power corrected for post-operative refraction. Results showed that the Pearce lens was about 4.3 diopters stronger than the average iridocapsular lens. Using the optical method, the final inaccuracy of the prediction, namely 1.5 diopters, could be completely explained by the inherent inaccuracies of the measuring system.