Hyperelastic Models of the Cornea in Ophthalmology

The study presents two problems of eye biomechanics in which hyperelastic materials are used to model the cornea. The first problem examines changes in the stress-strain state of the eyeball after the implantation of a MyoRing in patients with high myopia and thin corneas. A two-dimensional finite element model of the eye, consisting of two spherical layers loaded with intraocular pressure, is considered. An elastic ring is inserted into the cornea. A nonlinear axisymmetric contact problem is solved using the ANSYS software package. The nonlinear properties of the cornea are described using the Yeoh hyperelastic model, the Neo-Hookean model, and the two-parameter Mooney-Rivlin model. The changes in corneal curvature radius in response to ring insertion are compared for different corneal models. The numerical results demonstrate that hyperelastic models yield corneal deformations that align well with clinically observed changes. The second problem investigates changes in intraocular pressure during intravitreal injections. Finite element models of the eyeball are presented—without partitions, with one partition, and with two partitions—to assess intraocular pressure in the eye’s internal chambers during injections. Pressure changes in the chambers are evaluated for injections of 0.05 and 0.1 ml into the vitreous body. Simulations are performed for both transversely isotropic and hyperelastic corneal models.