Laser thermokeratoplast y (ltk): A finite element model of the cornea

Purpose. To investigate the influence of parameters on LTK that can hardly be obtained by experimental research arw to support the transfer of data from animal experiments to the situation in the hurmin eye. Methods. Three-dimensional models of the human and the porcine cornea were developed with the finite element method (FEM). The geometry and the material properties of the porcine cornea were determined experimentally whereas the data for the human models were taken from literature. The IR laser induced local contraction of the cornea was also quantified in preliminary experiments and was integrated by volume shrinkage as an input paramete into the FE models. Results The Young's modulus takes a strong influence on the results whereas the intraocular pressure only takes a minor influence. Based on the different geometry the human cornea requires less volume sirinkage than the porcine cornea in order to achieve the same refractive change. Although a ring coagulation pattern leads to a different global topography compare-l to a spot pattern, the resulting refractive change of the central cornea only differs slightly. Conclusions. The age dependency oft le corneal stiffness points towards the fact that it could be important to consider the patient's material properties of the cornea before applying LTK. The finite element mods! developed here can help to transfer data from animal models to the human eye and thereby to reduce the number of experiments.