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 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.

Rapid and precise in vivo measurement of human corneal thickness with optical low-coherence reflectometry in normal human eyes.

An optical low-coherence reflectometer is used for rapid noncontact measurements of the human corneal thickness in vivo. Thickness measurements on ten volunteers show a standard deviation of 3.4 µm. The experiments reveal that the optical reflectometer benefits from a 2.5 fold enhancement of the measurement precision and a 2.8 fold reduction in measurement time compared to a standard clinical ultrasonic pachometer. © 1998 Society of Photo-Optical Instrumentation Engineers.

Rapid and scalable scans at 21 m/s in optical low-coherence reflectometry.

An optical low-coherence reflectometer is presented that uses a fiber Michelson interferometer with a rotating cube to generate rapid depth scans at a high repetition rate. A folded optical path geometry allows the reference arm to scale up the scan range, scan speed, and scan repetitiveness. Thickness measurements with a repetitiveness of 384 Hz and a longitudinal scanning speed of 21 m/s in air over a range of ~3 mm are demonstrated.

[Changes occurring in psychotherapy measured by the Osgood semantic differential--methodologic elaboration]. / Changements survenus en psychothérapie mesurés à l'aide du différenciateur sémantique d'Osgood--élaboration méthodologique.

General recall on Osgood's semantic differential. Motive and way of integrating it in research on the effects of psychotherapies. Report of some preliminary results from a transversal study of normal, neurotic and schizophrenic subjects and from a longitudinal study of normal and neurotic subjects. These first results strengthen the assumption that the semantic differential provides an appreciably adequate picture of mental state, for both its stable and evolutive components.

Methodological aspects of the evaluation of psychotherapies.

With the aim of methodically examining the evaluation of short-term psychotherapies, the authors study the conditions of setting up and applying Osgood's semantic differential. For an ad hoc selection of the inducive words, an in-depth study of the parametrization of bipolar scales based on new premises is undertaken, after which the semantic space is reconstructed. These stages are carried out, on the one hand, on a sample of patients under treatment at a psychiatric policlinic, and on the other hand, on a sample drawn from the general population. The results are compared step for step. In addition, correspondence analyses between the inducive words and the scales shed new light on the stability of Osgood's semantic differential.