Comportamiento Viscoelástico del Tejido Corneal

The biomechanical study of the corneal tissue has been primarily focused on the cornea computational simulation under different stress-strain conditions. However, there is still very little information regarding the mechanical properties and response of the corneal tissue, information required to perform adequate numerical simulations. Taking this issue into account, stress relaxation displacement controlled tests and creep stress controlled tests were performed in order to characterize the time–dependent, viscoelastic behavior of corneal tissue. Vertical strips were obtained from porcine corneas and were subjected to uniaxial tensile tests under different stress-strain levels. A time dependent, viscoelastic behavior was initially observed for high stress levels and an empirical constitutive model is proposed based on the experimental data. Creep and relaxation tests at low stress levels, within physiological conditions, were also performed. Results indicate that the corneal tissue viscoelastic behavior may be neglected for low stress levels which considerably simplifies the constitutive model to be implemented in computational simulations.