Comparison of different techniques of anterior chamber depth and keratometric measurements

PURPOSE: To compare measurements of anterior chamber depth (ACD) and corneal curvature obtained with the Pentacam to other commonly used devices. DESIGN: Prospective, nonrandomized clinical trial. METHODS: Measurements of ACD and keratometry were prospectively obtained in 22 eyes of 11 subjects with the Pentacam compared with measurements of the ultrasound (US) A,scan and IOLMaster (ACD), and with those of automated keratometry (AK) and IOLMaster (keratometry) at the Assaf Harofeh Medical Center. RESULTS: The mean interdevice differences in keratometry for Pentacam vs AK, Pentacam vs IOLMaster, and AK vs IOLMaster were -0.046 diopters, -0-471 diopters, and -0.424 diopters, respectively. measurements of keratometry by the IOLMaster differed statistically significantly from those of Pentacam (P < .01) and AK (P < .01). For measurement of keratometry, 95% limits of agreement were -1.321 to 1.229 diopters for the Pentacam and AK, -1.478 to 0.536 diopters for the Pentacam and IOLMaster, and -1.026 to 0.178 diopters for the AK and IOLMaster. The mean interdevice differences in ACD for the Pentacam vs US, Pentacam vs IOLMaster, and US vs IOLMaster were 0.103, 0.099, and -0.004 mm, respectively. Measurements of ACD by the Pentacam differed statistically significantly from those of US (P < .05) and IOLMaster (P < .01). For measurement of ACD, 95% limits of agreement were -0.197 to 0.404 mm for the Pentacam and US, -0.169 to 0.367 mm for the Pentacam and IOLMaster, and -0.332 to 0.324 mm for the US and IOLMaster. CONCLUSIONS: For some clinical applications, measurements of ACD and corneal curvature with the tested machines may differ greatly and therefore may not be interchangeable.