The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOLMaster((TM))

dBackground. Axial length and anterior chamber depth have been measured cli nically using conventional ultrasound biometry. Recently, a non-contact dev ice has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device. Methods: The axial length and anterior chamber depth were measured by two p ractitioners on a group of young subjects using the IOLMaster (TM) followed by a conventional ultrasound biometer operated by a third practitioner. Th e accommodation was controlled in ultrasound biometry through a full correc tion on the non-measured eye and a distant fixation target. Results: There was good repeatability and accuracy of axial length assessme nt. The mean difference between the IOLMaster (TM) and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster (TM) and the differenc e was not significant. The anterior chamber depth was repeatable but was sh own to be deeper than the ultrasound results. The mean difference in anteri or chamber depth between the IOLMaster (TM) and ultrasound biometry was 0.1 5 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggest ed that the former device is not measuring the axial anterior chamber depth . Conclusions:The IOLMaster (TM) is a non-contact 'optical' A-scan which is s imple to use and good for axial length assessment. The anterior chamber dep th assessment should be further evaluated. (C) 2001 The College of Optometr ists. Published by Elsevier Science Ltd. All rights reserved.