Comparison of the Zeiss IOLMaster and applanation A-scan ultrasound: biometry for intraocular lens calculation.

PURPOSE: A comparison of axial length estimates using applanation A-scan ultrasound and the Zeiss IOLMaster was conducted. The accuracy in predicting postoperative refraction determined by each method was also compared. METHODS: A cross-sectional study was performed on 51 eyes in 46 patients presenting to clinical practice for cataract surgery assessment. Preoperative measurement of axial length was performed with applanation ultrasound and the IOLMaster. The IOLMaster measurements were used to determine the intraocular lens power based on the SRK/T formula. Postoperative refractive outcomes were obtained and spherical equivalent calculated and compared to the predicted refractive error with each biometric method. RESULTS: On average the axial lengths measured by the IOLMaster were longer by 0.15 mm compared to ultrasound biometry (P < 0.01). Using the IOLMaster over applanation ultrasound biometry significantly improved the postoperative refractive outcome from 0.65 D to 0.42 D (P = 0.011). CONCLUSIONS: The IOLMaster provides an accurate axial length measurement and results in accurate intraocular lens power calculation based on the SRK/T formula. It is quick and easy to use and provides a non-contact technique with no risk of infection or corneal abrasion.