1 June 1998 Corneal group refractive index measurement using low-coherence interferometry
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Proceedings Volume 3246, Ophthalmic Technologies VIII; (1998) https://doi.org/10.1117/12.309424
Event: BiOS '98 International Biomedical Optics Symposium, 1998, San Jose, CA, United States
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.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stephen R. Uhlhorn, Fabrice Manns, Hassan Tahi, Pascal O. Rol, Jean-Marie A. Parel, "Corneal group refractive index measurement using low-coherence interferometry", Proc. SPIE 3246, Ophthalmic Technologies VIII, (1 June 1998); doi: 10.1117/12.309424; https://doi.org/10.1117/12.309424
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