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Proceedings Paper

Interpretation of data obtained with a high-resolution height-measuring corneal topographer
Author(s): Franciscus H. M. Jongsma; Bertho A. Th. Stultiens; Fred Hendrikse
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Paper Abstract

Basically, other information becomes available when, instead of local slope, local height is measured. In contradistinction to the data obtained from Placido based systems, ambiguity can be avoided in the height data obtained from oblique projected grids on a diffusely reflecting surface, e.g., with an adapted set-up, discrimination between convex and concave surfaces is possible. We made a corneal topographer based on sodium-fluorescein installation in the precorneal tearfilm for obtaining a diffusely radiating surface. The local information available using a height measuring system, however, sometimes deviates from global information a.o. due to tearfilm breakup. This breakup may be controlled by applying artificial tear products. These products however, may influence the tearfilm thickness. With in vitro measurements we also obtained information about the thickness of a natural tearfilm that turned out to be at least several tens of micrometers s rather than 7 to 10 micrometers as is given in physiological handbooks. In this paper also a microslit-projection and observation method for direct tearlayer thickness measurements is described. The aim of this research is to investigate the maximum obtainable accuracy of measurements done in vivo and to optimize the sodium-fluorescein installation with respect to absorption of the excitation light and the fluorescent yield with minimum distortion of the natural corneal tearlayer.

Paper Details

Date Published: 1 February 1995
PDF: 5 pages
Proc. SPIE 2329, Optical and Imaging Techniques in Biomedicine, (1 February 1995); doi: 10.1117/12.200868
Show Author Affiliations
Franciscus H. M. Jongsma, Univ. Limburg (Netherlands)
Bertho A. Th. Stultiens, TLA Engineering (Netherlands)
Fred Hendrikse, Univ. Limburg (Netherlands)

Published in SPIE Proceedings Vol. 2329:
Optical and Imaging Techniques in Biomedicine
Hans-Jochen Foth; Aaron Lewis; Halina Podbielska; Michel Robert-Nicoud; Herbert Schneckenburger; Anthony J. Wilson, Editor(s)

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