title: Biomechanical and refractive behaviors of keratoconic cornea based on three-dimensional anisotropic hyperelastic models.
abstract: OBJECTIVE
  To investigate the biomechanical and refractive behaviors of normal and keratoconic corneas based on three-dimensional anisotropic hyperelastic corneal models with two layers.
  
  
  METHODS
  Based on an anisotropic hyperelastic formula, the finite element method was employed to develop normal and keratoconic corneal models in which the fiber orientations and the biomechanical differences between corneal layers were taken into account. The displacements for normal and keratoconic corneal models were studied, as well as changes in corneal refractive power with intraocular pressure (IOP).
  
  
  RESULTS
  There were different displacements for keratoconic and normal corneas. Positive correlations were found in the keratoconic cornea between IOP and apical displacement, as well as between IOP and corneal refractive power. Under normal IOP, both the corneal shape and refractive power map were affected by the stiffness distributions of the corneal layers.
  
  
  CONCLUSIONS
  Finite element analysis can be used to demonstrate the biomechanical and refractive behavior of a cornea with keratoconus. From a biomechanical viewpoint, the displacement changes seen under normal IOP were due to the decreased stiffness in the keratoconic corneal tissue and local thinning disorders. Thus, the curvature and corneal refractive power map will be abnormal in keratoconus.
authors.affiliation: School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Zhaolong
authors.initials: Z
authors.lastname: Han
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Sui
authors.forename: Dai
authors.initials: D
authors.lastname: Zhou
authors.forename: Chuanqing
authors.initials: C
authors.lastname: Zhou
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Ren
mesh_terms: D016880:Anisotropy; D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology*; D004548:Elasticity / Q000502:physiology; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007429:Intraocular Pressure / Q000502:physiology; D007640:Keratoconus / Q000503:physiopathology*; D008962:Models, Theoretical; D018583:Pliability / Q000502:physiology*; D012029:Refraction, Ocular / Q000502:physiology*