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

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.

Three-Dimensional Confocal Microscopy of the Living Human Eye

“…This study is a new application of clinical confocal microscopy to PRK patients. Although the corneal thickness was measured to a precision of approximately 20 microns, which is comparable with ultrasound, it should be pointed out that the new technique of optical low coherence reflectrometry routinely measures the corneal thickness with submicron precision (79,80).…”

Central corneal thickness in high myopia

“…The measurements of one subject were completed within 30 mins. The average intersession precision (SD) for five subjects was 1.0 mm corresponding with (Bo¨hnke et al 1999). High and low CCT values were determined with the same SD.…”

“…(Bo¨hnke et al (1999) reported a precision of about 1 mm (SD), an intrasession reproducibility around 0.9-1.2 mm and a high intersession reproducibility. Other studies have compared the OLCR pachymeter with the ultrasound pachymeter.…”

Anterior Eye Imaging with Optical Coherence Tomography

“…Central corneal thickness is routinely used to monitor corneal edema and endothelial function [26][27][28][29], manage ocular hypertension [30,31], and plan common keratorefractive surgeries such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Ultrasound pachymetry [32,33] and several other techniques [34][35][36][37] provide only spot measurements, while scanning-slit optical pachymetry [38,39], very high-frequency ultrasound imaging [40,41], and optical coherence tomography allow mapping of a wide area of the cornea. Pachymetric mapping provides several advantages over spot measurements.…”