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Journal of Biomedicine and Biotechnology
Volume 2011 (2011), Article ID 526705, 6 pages
http://dx.doi.org/10.1155/2011/526705
Research Article

Creep Behavior of Passive Bovine Extraocular Muscle

1Department of Ophthalmology, Jules Stein Eye Institute, University of California Los Angeles, 100 Stein Plaza, UCLA, Los Angeles, CA 90095-7002, USA
2Department of Mechanical Engineering, University of California, Los Angeles, CA, USA
3Biomedical Engineering Interdepartmental Program, University of California, Los Angeles, CA, USA
4Neuroscience Interdepartmental Program, University of California, Los Angeles, CA, USA
5Department of Neurology, University of California, Los Angeles, CA, USA

Received 6 June 2011; Accepted 16 August 2011

Academic Editor: Henk Granzier

Copyright © 2011 Lawrence Yoo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper characterized bovine extraocular muscles (EOMs) using creep, which represents long-term stretching induced by a constant force. After preliminary optimization of testing conditions, 20 fresh EOM samples were subjected to four different loading rates of 1.67, 3.33, 8.33, and 16.67%/s, after which creep was observed for 1,500 s. A published quasilinear viscoelastic (QLV) relaxation function was transformed to a creep function that was compared with data. Repeatable creep was observed for each loading rate and was similar among all six anatomical EOMs. The mean creep coefficient after 1,500 seconds for a wide range of initial loading rates was at (standard deviation, SD). The creep function derived from the relaxation-based QLV model agreed with observed creep to within 2.7% following 16.67%/s ramp loading. Measured creep agrees closely with a derived QLV model of EOM relaxation, validating a previous QLV model for characterization of EOM biomechanics.