Corneal group refractive index measurement using low-coherence interferometry

Stephen R. Uhlhorn, Fabrice Manns, Hassan Tahi, Pascal Rol, Jean Marie Parel

Research output: Contribution to journalConference article

11 Scopus citations

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 λ = 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 = 1.450 +/- 0.024 for the human cornea, which is much higher than a calculated group refractive index of ng = 1.387. Because of dehydration, the optical thickness of the cornea decreased at a rate of 5.5 μm/min which led to an artificially high value for the group refractive index. Conclusion. The calculated group refractive index of ng = 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.

Original languageEnglish (US)
Pages (from-to)14-21
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3246
DOIs
StatePublished - Dec 1 1998
EventProceedings of Ophthalmic Technologies VIII - San Jose, CA, United States
Duration: Jan 24 1998Jan 25 1998

Keywords

  • Cornea
  • Low-coherence interferometry
  • Refractive index

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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