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. Author manuscript; available in PMC: 2009 Jun 5.
Published in final edited form as: Exp Eye Res. 2006 May 23;83(4):709–720. doi: 10.1016/j.exer.2006.03.015

Figure 3.

Figure 3

Experiments illustrating elastic and viscoelastic properties in a 7mm, full-thickness horizontal corneal strip from a 63 year old donor. Elliptical polarization allows visualization of non-homogeneous internal stresses. Progressive stretching of the sample (1, 2 and 3) and measurement of the induced load (stress) allows calculation of the elastic (Young’s) modulus from the slope of the stress-strain relationship. The relationship is nonlinear. A second experiment in which a constant displacement is imposed in the same sample demonstrates time-dependent stress relaxation, a viscoelastic property of biological soft tissues (4 and 5). Courtesy of W.J. Dupps, Jr., MD, PhD and T. Doehring, PhD.