Research Papers: Sensing

Tear film measurement by optical reflectometry technique

[+] Author Affiliations
Hui Lu

University of Miami, Department of Electrical and Computer Engineering, Coral Gables, Florida 33146

Michael R. Wang

University of Miami, Department of Electrical and Computer Engineering, Coral Gables, Florida 33146

Jianhua Wang

University of Miami, Bascom Palmer Eye Institute, Miami, Florida 33136

Meixiao Shen

University of Miami, Bascom Palmer Eye Institute, Miami, Florida 33136

J. Biomed. Opt. 19(2), 027001 (Feb 06, 2014). doi:10.1117/1.JBO.19.2.027001
History: Received November 7, 2013; Revised December 30, 2013; Accepted December 31, 2013
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Abstract.  Evaluation of tear film is performed by an optical reflectometer system with alignment guided by a galvanometer scanner. The reflectometer system utilizes optical fibers to deliver illumination light to the tear film and collect the film reflectance as a function of wavelength. Film thickness is determined by best fitting the reflectance-wavelength curve. The spectral reflectance acquisition time is 15 ms, fast enough for detecting film thickness changes. Fast beam alignment of 1 s is achieved by the galvanometer scanner. The reflectometer was first used to evaluate artificial tear film on a model eye with and without a contact lens. The film thickness and thinning rate have been successfully quantified with the minimum measured thickness of about 0.3 μm. Tear films in human eyes, with and without a contact lens, have also been evaluated. A high-contrast spectral reflectance signal from the precontact lens tear film is clearly observed, and the thinning dynamics have been easily recorded from 3.69 to 1.31 μm with lipid layer thickness variation in the range of 41 to 67 nm. The accuracy of the measurement is better than ±0.58% of the film thickness at an estimated tear film refractive index error of ±0.001. The fiber-based reflectometer system is compact and easy to handle.

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© 2014 Society of Photo-Optical Instrumentation Engineers

Citation

Hui Lu ; Michael R. Wang ; Jianhua Wang and Meixiao Shen
"Tear film measurement by optical reflectometry technique", J. Biomed. Opt. 19(2), 027001 (Feb 06, 2014). ; http://dx.doi.org/10.1117/1.JBO.19.2.027001


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