Objective: The aim of this study is to investigate the accuracy of optical biometer and a–scan for the power calculation of intraocular lenses at SMS Medical college ,jaipur . Materials and Methods: We examined consecutive cataractous eyes with the optical biometer as well as with the acoustic biometry and keratometry. In all eyes, the intraocular lens to be implanted was chosen by means of the SRK/T formula, based on the measurements conducted with our standard method. The achieved postoperative refraction is obtained, at least 4 weeks after surgery, by the treating ophthalmologists. The results were compared and analyzed statistically . Results: We examined 86 out of which 36 female and 42 were male. Comparison of eye lengths as well as of the keratometric measurements showed good correspondence between the obtained measurements by both methods, acoustic biometry yielding significantly (P < 0.001) different axial lengths than the optical biometer, and the keratometry yielding significantly (P < 0.001) different mean corneal refraction power than the IOL Master. The accuracy of the refraction obtained postoperatively compared to the preoperative aim was better with optical biometer compared to acoustic method. Conclusions: The predicted systemic differences in measurement results could be verified. Significant improvement in accuracy of our postoperative refraction prediction was achieved using IOL master. The other advantages of the optical biometer are the substantial gain in time, as well as the fact that performance of the measurements may be delegated. Only shortcoming was the use of optical biometer in mature cataract.