title: Finite-element modeling of posterior lamellar keratoplasty: construction of theoretical nomograms for induced refractive errors.
abstract: OBJECTIVE
  To estimate the theoretical corneal refractive error induced by mechanical weakening effects from posterior lamellar keratoplasty (PLKP) in the human cornea.
  
  
  METHODS
  The refractive effects of PLKP are simulated by finite-element modeling (FEM) as a mathematical function of the thickness of the excised posterior lamellar corneal button, with a nonlinear formulation of stress-strain relation for the corneal material. A theoretical nomogram was developed to correlate the refractive changes to button thickness.
  
  
  RESULTS
  The predicted refractive change after PLKP is less than 1 dpt for a 170-microm thickness posterior corneal button over a broad range of Young's modulus. Thicker buttons result in greater surgically induced refractive errors.
  
  
  CONCLUSIONS
  According to FEM analysis, the excision of a posterior lamellar button of less than 170 microm thickness produces a minimal predicted refractive change (< 1 dpt) in the cornea after PLKP.
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan College of Engineering, Ann Arbor, MI, USA.
authors.forename: Gagik P
authors.initials: GP
authors.lastname: Djotyan
authors.forename: H Kaz
authors.initials: HK
authors.lastname: Soong
authors.forename: Shahzad
authors.initials: S
authors.lastname: Mian
authors.forename: Delia C
authors.initials: DC
authors.lastname: Fernández
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Kurtz
authors.forename: Tibor
authors.initials: T
authors.lastname: Juhasz
mesh_terms: D001696:Biomechanical Phenomena; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D016039:Corneal Transplantation / Q000009:adverse effects*; D020342:Finite Element Analysis; D006801:Humans; D008962:Models, Theoretical; D049451:Nomograms; D011183:Postoperative Complications; D012030:Refractive Errors / Q000209:etiology*