Characterization of Human Cornea Using an Anisotropic Fiber Reinforced Model and Inverse Finite Element Analysis

The purpose of the present study is to predict the transient response of the human cornea via a structural model appropriately representing its biomechanical behavior. Load bearing characteristics of the cornea remain poorly understood due to the complexity of its constitutive model. A constitutive model that captures the response of cornea over the whole experimental time and incorporates all included nonlinearities is necessary. In the current study, parameters of the structural anisotropic fiber-reinforced hyper-viscoelastic model have been obtained using coupled finite element-optimization analysis and the uniaxial tensile test for three different strain rates. The utilized model accounts for the dispersion of the fibers along with their reorientation during loading, the nonlinear behavior of finite tissue deformation, and the intrinsic viscoelastic property of the matrix. Results show that the higher the strain rate the higher the stiffness of tested samples. Samples showed stiffening behavior specially at the end section of the tissue response for slower tensile rates. Eventually, the model behavior and its connection with its micro structures such as the collagen fibers, have been investigated. Examining the results shows that the numerical simulations performed for the prediction of the cornea tissue behavior are in agreement with the experimental results.