This study addresses two problems in eye biomechanics: myopia correction surgery through MyoRing implantation and changes in intraocular pressure during intravitreal injections. Finite element modeling of the outer eye shell under intraocular pressure was performed using the ANSYS software package. The cornea is defined as a spherical segment with a smaller radius and variable thickness. To describe its nonlinear properties, hyperelastic material models were used (Yeoh model, Neo-Hookean model, and two-parameter Mooney-Rivlin model). A comparison is made with models where the cornea is modeled as a transversely isotropic biological tissue. In the first case, the nonlinear problem of changes in the eye’s stress-strain state with an elastic insert in the cornea is solved. The ring implantation process is simulated using contact pairs and a sequential load application method. The calculations showed that during MyoRing implantation, the cornea experiences significant shear deformations. Results consistent with clinical data were only achieved using hyperelastic material models. Moreover, a sufficiently accurate solution was obtained using the Neo-Hookean material, whose potential depends on just one parameter. In the second task, for two different corneal material models (transversely isotropic and hyperelastic), the change in intraocular pressure during intravitreal injections is analyzed. A comparison of three models is conducted: without septa, with one septum, and with two septa. Based on the calculations, the pressure levels in the eye chambers were evaluated depending on the volume of the injected drug and the septum configuration. The calculations showed close results for the transversely isotropic and hyperelastic corneal models. Consequently, the added complexity in modeling associated with describing the hyperelastic properties of the cornea appears to be unjustified.

Svetlana M. Bauer, Doctor of Physical and Mathematical Sciences, Professor, Head of the Department of Theoretical and Applied Mechanics; e-mail: s.bauer@spbu.ru; https://orcid.org/0000-0003-3732-2110; AuthorID: 6610

Lyudmila A. Venatovskaya Candidate of Physical and Mathematical Sciences, Associate Professor; e-mail: l.venatovskaya@spbu.ru; https://orcid.org/0000-0002-0813-3727; AuthorID: 742317

Dmitriy V. Matchenko Student; e-mail: dmitriy.matchenko@yahoo.com; https://orci d.org/0009-0006-2638-2977; AuthorID: 1308371