Precision and reproducibility of measurements of human corneal thickness with rapid optical low-coherence reflectometry (OLCR)

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 instr ument, attached to a slit lamp, is a single mode fiber optic based Michelso n interferometer with a high repetition rate as previously described. The s ame operator performed ten sets of measurements on the same subject, each c onsisting 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 518-52 1) mu m on day 1, 519.9 +/- 0.9 (range 519-521) mu m on day 2, and 523.8 +/ - 0.65 (range 523-525) mu m 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 precious days (p < 0.001, one way analysis of varian ce). Optical low-coherence reflectometry measurements of corneal thickness can be performed with high precision of about 1 mu m and a high intra- and intersession reproducibility. (C) 1999 Society of Photo-Optical Instrumenta tion Engineers. [S1083-3668(99)01301-5].