Computer Modelling of Thin, Soft Biological Tissues: A Decoupled Strategy for Standardizing Isotropic and Anisotropic Corneal Biomechanics

The development of accurate digital twin models of the human cornea is a key factor for planning and monitoring eye treatments and clinical supervision. Corneal tissue can be simulated with the implementation of hyperelastic models based on strain energy density functions. However, the number of hyperelastic models and the parameters’ variation that define these models hinder comparison across different studies. Furthermore, parameter calculations based on a single test are an ill-posed problem. In this research, a novel sequential methodology based on collagen fibril crimping strain threshold has been implemented to calculate the corneal material’s parameters. As an application case, this method has been applied to a hyperelastic Holzapfel–Gasser–Ogden (HGO) model to calculate the isotropic parameters associated with low stretch levels and the anisotropic parameters that consider the collagen fibres’ contribution at higher deformations. The sequential test combination applied to a standardized hyperelastic material model could contribute to ensuring physically meaningful and consistent material parameters, the comparison of different investigations, and the development of an accurate in silico patient-specific cornea model for clinical applications.