Interpretation of data obtained with a high-resolution height measuring corneal topographer

Franciscus H. M. Jongsma; Bertho A. Th. Stultiens; Fred Hendrikse

doi:10.1117/12.200868

1 February 1995 Interpretation of data obtained with a high-resolution height-measuring corneal topographer

Franciscus H. M. Jongsma, Bertho A. Th. Stultiens, Fred Hendrikse

Proceedings Volume 2329, Optical and Imaging Techniques in Biomedicine; (1995) https://doi.org/10.1117/12.200868
Event: International Symposium on Biomedical Optics Europe '94, 1994, Lille, France

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.

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Franciscus H. M. Jongsma, Bertho A. Th. Stultiens, and Fred Hendrikse "Interpretation of data obtained with a high-resolution height-measuring corneal topographer", Proc. SPIE 2329, Optical and Imaging Techniques in Biomedicine, (1 February 1995); https://doi.org/10.1117/12.200868

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KEYWORDS

Sodium

Luminescence

Cornea

Eye

In vitro testing

In vivo imaging

Measurement devices

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