Assessment of the ex vivo biomechanical properties of porcine cornea with inflation test for corneal xenotransplantation

Abstract

Objective: This study aims to obtain the biomechanical properties of porcine cornea so as to provide necessary biomechanical experimental basis for pig-to-human corneal xenotransplantation. Methods: Seventeen fresh porcine corneal specimens obtained from pigs aged 4–6 months were examined under inflation conditions to determine the constitutive relationships of the material through dynamic loading conditions (pressure range: 1.47–42.66 mmHg). The forward deflection of porcine anterior corneal apex was measured by the laser displacement sensor. The pressure deformation results were analysed on the basis of shell theory to estimate Young’s modulus of the cornea and derive its relationship with intraocular pressure (IOP). Results: The porcine corneas showed a nonlinear corneal forward displacement/IOP and stress/strain relationship with an initial low stiffness stage and a later high stiffness stage. In spite of the nonlinearity between the internal pressure and apex forward deflection, the relationship between the Young’s modulus and the IOP was almost linear. Conclusions: Compared with human corneas, porcine corneas exhibited a similar nonlinear behaviour but lower stiffness values. The biomechanical parameters of porcine cornea obtained from this test could be applied to numerical simulations of refractive surgery procedures and lay a foundation for pig-to-human corneal xenotransplantation.