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Proceedings Paper

Corneal group refractive index measurement using low-coherence interferometry
Author(s): Stephen R. Uhlhorn; Fabrice Manns; Hassan Tahi; Pascal O. Rol; Jean-Marie A. Parel
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Paper Abstract

Purpose: The goal of the study is to measure the group refractive index of the human cornea in vitro to improve the accuracy of corneal thickness measurements. Methods: Corneal buttons were trephined from 23 human cadaver eyes and the group refractive index of the cornea was measured at lambda equals 840 nm using a low-coherence Michelson interferometer and the technique proposed by Sorin and Gray (Phot. Tech. Lett. 4:105 - 107, 1992). The effect of dehydration on the measurement was studied by measuring the corneal optical thickness as a function of time. Results: Preliminary measurements of the group refractive index at 840 nm gave ng equals 1.450 plus or minus 0.024 for the human cornea, which is much higher than a calculated group refractive index of ng equals 1.387. Because of dehydration, the optical thickness of the cornea decreased at a rate of 5.5 micrometer/minute which led to an artificially high value for the group refractive index. Conclusion: The calculated group refractive index of ng equals 1.387 appears to be an accurate value for the purpose of corneal thickness measurements using low-coherence interferometry, and corneal group refractive index measurements can be performed in vitro if the measurements are performed rapidly to avoid the effect of dehydration.

Paper Details

Date Published: 1 June 1998
PDF: 8 pages
Proc. SPIE 3246, Ophthalmic Technologies VIII, (1 June 1998); doi: 10.1117/12.309424
Show Author Affiliations
Stephen R. Uhlhorn, Univ. of Miami and Bascom Palmer Eye Institute/Univ. of Miami School of Medicine (United States)
Fabrice Manns, Univ. of Miami and Bascom Palmer Eye Institute/Univ. of Miami School of Medicine (United States)
Hassan Tahi, Bascom Eye Institute/Univ. of Miami School of Medicine (United States)
Pascal O. Rol, Univ. of Miami and Bascom Palmer Eye Institute/Univ. of Miami School of Medicine and Univ. (Switzerland)
Jean-Marie A. Parel, Univ. of Miami and Bascom Palmer Eye Institute/Univ. of Miami School of Medicine (United States)


Published in SPIE Proceedings Vol. 3246:
Ophthalmic Technologies VIII
Pascal O. Rol; Karen Margaret Joos; Fabrice Manns, Editor(s)

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