Estimation of the elastic characteristics of the eyeball from the response of the enucleated eye to the introduction of given volumes of liquid

Mathematical modelling of the deformation of the eyeball under the action of internal pressure is performed. The modelling is carried out within the framework of the general approach developed by the authors, which represents the eyeball as a set of a deformable two-dimensional surface (cornea) and a zero-dimensional element that responds with a change in volume to changes in intraocular pressure (scleral region). The calculation results are compared with the experimental data presented in the literature, which are obtained on the enucleated human eyes. It is concluded that the experimentally observed nonlinearity of the dependence of the intraocular volume on pressure is determined by the nonlinearity of the elastic behavior of the cornea, while the scleral region in the studied pressure range is deformed almost linearly. The values of the constants present in the model (corneal and scleral stiffnesses and a parameter that determines the nonlinearity of elastic corneal deformation) are estimated. The values of the elastic moduli turned out to be close to the estimates previously obtained by the authors on the basis of measurements performed on the living eye. The value of the nonlinearity parameter of the cornea, determined from measurements on the whole enucleated eye, turned out to be close to the values estimated by the authors on the basis of data from experiments with an isolated cornea, but slightly lower on average. The individual values of all elastic parameters for specific examined eyes differ markedly from each other.