Share Email Print
cover

Proceedings Paper

In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain OCT and an efficient delay estimator
Author(s): Valentin Aranha dos Santos; Leopold Schmetterer; Martin Gröschl; Gerhard Garhofer; René M. Werkmeister
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

Dry eye syndrome is a highly prevalent disease of the ocular surface characterized by an instability of the tear film. Traditional methods used for the evaluation of tear film stability are invasive or show limited repeatability. Here we propose a new noninvasive approach to measure tear film thickness using an efficient delay estimator and ultrahigh resolution spectral domain OCT. Silicon wafer phantoms with layers of known thickness and group index were used to validate the estimator-based thickness measurement. A theoretical analysis of the fundamental limit of the precision of the estimator is presented and the analytical expression of the Cramér-Rao lower bound (CRLB), which is the minimum variance that may be achieved by any unbiased estimator, is derived. The performance of the estimator against noise was investigated using simulations. We found that the proposed estimator reaches the CRLB associated with the OCT amplitude signal. The technique was applied in vivo in healthy subjects and dry eye patients. Series of tear film thickness maps were generated, allowing for the visualization of tear film dynamics. Our results show that the central tear film thickness precisely measured in vivo with a coefficient of variation of about 0.65% and that repeatable tear film dynamics can be observed. The presented method has the potential of being an alternative to breakup time measurements (BUT) and could be used in clinical setting to study patients with dry eye disease and monitor their treatments.

Paper Details

Date Published: 8 March 2016
PDF: 11 pages
Proc. SPIE 9697, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XX, 969706 (8 March 2016); doi: 10.1117/12.2208338
Show Author Affiliations
Valentin Aranha dos Santos, Medizinische Univ. Wien (Austria)
Technische Univ. Wien (Austria)
Leopold Schmetterer, Medizinische Univ. Wien (Austria)
Martin Gröschl, Technische Univ. Wien (Austria)
Gerhard Garhofer, Medizinische Univ. Wien (Austria)
René M. Werkmeister, Medizinische Univ. Wien (Austria)


Published in SPIE Proceedings Vol. 9697:
Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XX
Joseph A. Izatt; James G. Fujimoto; Valery V. Tuchin, Editor(s)

© SPIE. Terms of Use
Back to Top