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H Sheng, C Bottjer, MA Bullimore; Ocular Component Measurement Using the Zeiss IOLMaster . Invest. Ophthalmol. Vis. Sci. 2002;43(13):357.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Axial length and anterior chamber depth are usually measured using A-scan ultrasound. The IOLMaster is a new instrument that uses partial coherence interferometry to measure axial length and lateral slit illumination to measure the anterior chamber depth. We compared the repeatability of the IOLMaster and ultrasound. Methods: Axial length and the anterior chamber depth were measured on two occasions separated by 1-2 weeks in 20 young adults. Two examiners each took five readings with the IOLMaster of axial length and three readings of anterior chamber depth. The subject was then cyclopleged with 1% tropicamide. The IOLMaster readings were then repeated by both examiners, followed by ultrasound. Five readings of axial length were taken for both IOLMaster and ultrasound. Repeatability was evaluated by calculating the difference between measurements from the two occasions. The mean and standard deviation of these differences was then used to determine the 95% limits of agreement for each technique. In addition, the agreement between the IOLMaster and ultrasound and the effect of cycloplegia on IOLMaster readings were assessed using the same approach. Results: The IOLMaster was considerably more repeatable than ultrasound for axial length and anterior chamber depth measurement. The 95% limits of agreement for axial length measurement were -0.11 to +0.07 mm, -0.06 to +0.05 mm, -0.25 to +0.35 mm, for non-cyclopleged IOLMaster, cyclopleged IOLMaster, and ultrasound, respectively. The 95% limits of agreement for anterior chamber depth measurement were -0.11 to +0.18 mm, -0.06 to +0.04 mm, -0.19 to +0.21 mm, for non-cyclopleged IOLMaster, cyclopleged IOLMaster, and ultrasound, respectively. The two instruments showed good agreement with each other for cyclopleged measurements on axial length (95% limits of agreement = -0.39 to +0.64 mm). The IOLMaster gave significantly (p < 0.01) larger anterior chamber depths than ultrasound (mean = +0.18 mm; 95% limits of agreement = -0.02 to 0.37). Cycloplegia had no significant effect on IOLMaster measurements. Conclusion: The superior repeatability of the IOLMaster suggests that it should become the standard for axial length measurement in studies of myopia and refractive error. Its 95% limits of agreement correspond to a change in refractive error of 0.12 D.
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