Effects of strain rate on the mechanical properties of posterior rabbit sclera

We investigate the strain rate dependence of posterior rabbit sclera. The material properties of the sclera can serve as a direct estimate of the properties of the lamina cribrosa and other ocular load bearing tissues that cannot be tested directly. Knowledge of the behavior of these tissues is necessary to develop computational models of the posterior pole to investigate the role of increased intraocular pressure (IOP) in glaucoma. We tested posterior rabbit sclera in tension to determine the effects of two different strain rates (0.1%/sec and 10%/sec) on its material properties. Modulus (1-5% strain) showed a significant increase (256%) from 8.22 MPa at 0.1%/sec to 29.3 MPa at 10%/sec. Strain energy density (0-10% strain) also showed a significant increase (151%) from 0.0621 MPa at 0.1%/sec to 0.156 MPa at 10%/sec. The material properties of posterior rabbit sclera exhibit high strain rate sensitivity (a viscoelastic trait) and slight nonlinearity, but a strong nonlinear response was not observed.