Accuracy of intraocular lens power calculations using the Zeiss IOL master. A prospective study.

PURPOSE Partial Coherence Interferometry (PCI) is a fast, noncontact method to calculate lens implant power for cataract surgery. It has been reported as a potentially more accurate method than ultrasound biometry. Prospective study of the refractive outcomes of a consecutive series of patients undergoing phacoemulsification surgery with preoperative biometry by both ultrasound A-scan and PCI. METHODS A series of 50 eyes of 35 patients underwent small-incision phacoemulsification cataract surgery and lens implantation by one single surgeon. All patients had preoperative biometry performed by both ultrasound using the Sonomed and IOL Master optical biometry. The IOL Master results were included in the SRK II formula to calculate the lens implant power. Postoperative refractive assessment was performed 4 weeks after surgery. RESULTS The mean difference in axial length between ultrasound and optical biometry was 0.2 mm. The IOL Master measures a longer axial length. The mean keratometric power using the Javal instrument was 43.4 D and for the Zeiss IOL Master it was 42.9 D. At the week 4 postsurgery assessment, the overall refractive outcome was in the range of +/- 1D. Five patients were unable to undergo PCI biometry due to the density of cataract. CONCLUSIONS Intraocular lens power calculations using the Zeiss IOL Master are easy to perform and result in excellent refractive outcomes. A-scan biometry is still needed in case of mature cataract.