Precision and Reproducibility of Measurements of Human Corneal Thickness with Rapid Optical Low-Coherence Reflectometry (OLCR)

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Abstract
This study investigates the precision and intraindividual variability of a clinical optical pachometer based on low-coherence reflectometry, which was used to measure the central thickness of a human cornea in vivo. The instrument, attached to a slit lamp, is a single mode fiber optic based Michelson interferometer with a high repetition rate as previously described. The same operator performed ten sets of measurements on the same subject, each consisting of 20 consecutive scans, on each day for three consecutive days. By computing the means from every scan series, the thickness of the central cornea with optical pachometry was found to be 519.6±1.2 (range 518-521) μm on day 1, 519.9±0.9 (range 519-521) μm on day 2, and 523.8±0.6 (range 523-525) μm on day 3. The thickness values on day 3, where the subject suffered from a cold without clinical ocular involvement, were different from the two previous days (p<0.001, one way analysis of variance). Optical low-coherence reflectometry measurements of corneal thickness can be performed with high precision of about 1 μm and a high intra- and intersession reproducibility. © 1999 Society of Photo-Optical Instrumentation Engineers.