A finite element model of the cornea has been constructed on the basis of the mechanical properties of its ultrastructural elements which predicts the outcome of radial keratotomy operations in a satisfactory manner. The objective of this proposal is to refine and critically test the model. These refinements will include the nonlinearity of the stress-strain relationship of the collagen fibrils and will account for the shear stiffness of the ground substance that will allow the transmission of tensile forces from one fibril to its neighbors. The shift in fluid within the tissue that occurs when it is distorted will also be allowed for. These mechanical properties will be measured in isolated tissue and introduced into the model. The model will be verified by measuring the distortion of human corneas by measuring their contours photographically and by interference holography. Distortions will be effected by raising the intraocular pressure, indenting or applanating the cornea under a load and by creating a localized thinning of the stroma by evaporation or pressure. The same tests will be carried out on eyes that have undergone keratoplasty and the results compared with the predictions of the model.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY009284-02
Application #
3266670
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1991-07-01
Project End
1994-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Stanford University
Department
Type
Schools of Engineering
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305