Craig Foster, Civil and Materials Engineering and Sandeep Jain and Dimitri Azar, Ophthalmology and Visual Science, Philip Iannoccone, Children’s Memorial Hospital Primary Grant Support: NIH, UIC
Problem Statement and Motivation • • • Collagen cross-linking stiffens corneas weakened by keratoconus
Finite element modeling can help optimize procedure
We are developing models of normal, keratoconic, and and collagen cross-link treated corneas to determine quantities such as strain, stress, stiffness, and and shape under intraocular pressure. One major goal is to examine how the mechanical state of stress and strain influences patterns observed in cell formation and migration, including spiral formation in the epithelium. A second goal is to develop a model that can be used to predict the outcome of a specific treatment regimen of collagen cross-linking on a specific patient.
Cross-linking increases number of bonds between collagen fibers
Key Achievements and Future Goals
Technical Approach •
Multiscale models are developed using the stiffness curves of collagen fibrils oriented in different directions in the cornea (see below) and implemented in a finite element code.
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Once the traction-free geometry is determined, the intraocular pressure is added, and displace, strain, stress and other quantities of interest are determined.
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Development of anisotropic models based fibril orientation completed Parameter fitting and experimental validation under way Future work includes extending models to keratoconicc corneas and determining effect on cell pattern formation
Shear stress in a preliminary cornea model
Approximate orientations of collagen in the cornea