Biomechanical model of corneal transplantation.
OBJECTIVE
Refractive consequences of corneal transplants are analyzed using corneal biomechanical models assuming homogeneous and inhomogeneous stiffness distributions across the cornea. Additionally, refractive effects of grafts combined with volume removal procedures are also evaluated to develop methods to reduce postoperative refractive management of patients.


METHODS
Refinements of a two-dimensional finite element model are applied to simulate the biomechanical and refractive effects of different corneal transplant procedures: anterior lamellar keratoplasty, posterior lamellar keratoplasty, and penetrating keratoplasty. The models are based on a nonlinearly elastic, isotropic formulation. Predictions are compared with published clinical data.


RESULTS
The model simulating the penetrating keratoplasty procedure predicts more change in the postoperative corneal curvature than models simulating anterior lamellar keratoplasty or posterior lamellar keratoplasty procedures. When a lenticle-shaped tissue with a central thickness of 50 microns and a diameter of 4 mm is removed from the anterior corneal surface along with the anterior lamellar keratoplasty or posterior lamellar keratoplasty, the models predict a refractive correction of -8.6 and -8.9 diopters, respectively.


CONCLUSIONS
Simulations indicate that a posterior lamellar keratoplasty procedure is preferable for obtaining a better corneal curvature profile, eliminating the need for specific secondary treatments.
Cabrera Fernández
D
D
Bascom Palmer Eye Institute, the Department of Ophthalmology, University of Miami Miller School of Medicine, FL 33136, USA. dcabrera2@med.miami.edu
Niazy
A M
AM
Kurtz
R M
RM
Djotyan
G P
GP
Juhasz
T
T
D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery; D016039:Corneal Transplantation / Q000502:physiology*; D020342:Finite Element Analysis; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D011237:Predictive Value of Tests; D012029:Refraction, Ocular / Q000502:physiology