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Biometric assessment of anterior segment structures and anatomy is pivotal in the diagnosis and planning of corneal refractive and anterior segment surgery. Quantitative information and qualitative high-resolution imaging of individual corneal layers, anterior chamber dimensions, the irido-corneal angle, posterior chamber, crystalline lens, and ciliary body anatomy are becoming increasingly incorporated into the standard preoperative evaluation process. For the purposes of this report, we defined anterior segment scanning technology as scanning technology that produces two-dimensional cross-sectional images of the cornea and/or anterior segment. Technology relating to corneal shape and curvature data and/or topography was not included.
Only a limited number of studies reporting resolution and repeatability data of anterior segment biometry have been published in the peer-reviewed literature. In addition, published reports vary in methodology for reporting repeatability data, rendering it difficult to compare instruments. Accuracy, repeatability, and reproducibility often are inaccurately interchanged due to an apparent range of understanding in the specific definition of terms. For example, repeatability should be reported as either the standard deviation of repeated measurements, the coefficient of repeatability, or the coefficient of variation, all of which may be derived from one another. Some reports provide the intraclass correlation coefficient (ICC), which, in contrast, cannot be directly compared with the aforementioned parameters.
The primary aim of this report was to provide objective, standardized, cross-platform comparison of resolution and repeatability. The secondary aim was to provide a comprehensive review of published repeatability data for selected high-resolution anterior segment imaging and biometry devices.
Methods
Study Design
A standard letter (Appendix A, available in the PDF version of this article) was sent on the May 30, 2008, to 13 manufacturers for the following devices: Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany), Orbscan (Bausch & Lomb, Salt Lake City, Utah), Galilei (Ziemer, Port, Switzerland), Visante OCT (Carl Zeiss Meditec, Jena, Germany), SL-OCT (Heidelberg, Heidelberg, Germany), RTVue (Optovue, Fremont, California), OTI OCT (OTI, Miami, Florida), Artemis (ArcScan, Morrison, Colorado), UBM 60 (Paradigm, Salt Lake City, Utah), Vumax (Sonomed, Lake Success, New York), HiScan (Optikon, Rome, Italy), Lin50 (Quantel Medical, Clermont-Ferrand, France), and Eye Cubed (Ellex/Innovative, Adelaide, Australia). Each manufacturer was given 3 months to provide resolution and repeatability data for its device. If according to the definitions provided (see below), peer-reviewed published data were not available,...