Estudio Paramétrico en un Modelo en Elementos Finitos de la Córnea. Modelo Estático Lineal y no Lineal

Abstract

[Introduction] The biomechanic model of the cornea by using fmite elements [I) presents simplifications that can reduce the predictability of the result of the refractive surgery due to the high variability of the parameters of the surgery itself and of the structure of the cornea.
[Materials and methods) fu this work we accomplished a study of the sensitivity of certain parameters on the topographic result of simulations with and without surgical incisions. We have taken into account the linear and non-linear cases, both of geometric and material type, the boundary conditions with and without limbus, different models of the material (i.e. orthotropicity, multilayer structure of the cornea: Bowman membrane, the stroma and Descemet membrane), the model of the incision, the initial conditions, in three dimensional problems. It was accomplished a refmement study of the mesh in the
incisions, in the central or optical zone and in the limbus. We considered the corneal structure alone and as part of the whole eye fixed to the optical nerve in the posterior pole. We used the program of fmite element analysis OOFELIE that permits the development using a library of object oriented classes and SAMCEF.
[Results) The elastic, lineal and isotropic tissue model behaves well simulating the arcuate incision. By using pairs of arcuates, it is not posible to reach a steepening/flattening ratio lower than one. This ratio is
reached by increasing the refmement and using a model with geometric nonlinearity.
[Condulions) It is necesary to take into account the geometric nonlinearity to simulate the arcuate incisions. The computational simulation increased the comprehension of this type of incision, and allows better prediction of the refractive results.