Numerical prediction of laser refractive corneal surgery

PURPOSE: The finite element method was used to predict the change in the shape of the human cornea resulting from ablation of stromal tissue. The numerical method was able to evaluate the change of the dioptric power resulting from laser surgery such as photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and laser subepithelial keratomileusis (LASEK). METHODS: A 3D finite kinematics numerical model of the human cornea was developed. The solid geometry was defined by personalized geometrical data, and was discretized into finite elements by an automatic procedure which recovers the stress-free configuration. A two-fiber reinforced hyperelastic material model, which accounts for the organization of the anisotropic collagen structure, was adopted to describe the stromal tissue. For the simulation of surgical correction of myopic, hyperopic and astigmatic eyes, a corneal reshaping procedure based on standard ablation profiles was included into the code. RESULTS: Numerical results provide the postoperative shape of the cornea, the corrected refractive power, and the distribution of the stress and the strain through the stromal tissue. Examples of applications demonstrate the ability of the proposed model in predicting the outcomes of the refractive surgery. CONCLUSIONS: The cornea model described here may be adapted to individual cases in terms of material properties and of geometry. The availability of preoperative and postoperative stress fields is of primary importance in the planning of refractive surgery for problematic or degenerated corneas.

@TechReport{AFF06a,
  author       = {Anna, P. and Fotia, G. and Federico, M.},
  title        = {Numerical prediction of laser refractive corneal surgery},
  institution  = {CRS4, Center for Advanced Studies, Research and Development in Sardinia},
  number       = {06/25},
  month        = {april},
  year         = {2006},
  address      = {Cagliari, Italy}},
  type         = {Technical report},
  keywords     = {computational medicine, cardiac simulation, finite elements, simulation, mathematical modeling, bioinformatics},
  url          = {https://publications.crs4.it/pubdocs/2006/AFF06a},
}