Pre- and Post-processing for the Finite Element Model of Cornea for Collagen Crosslinking Treatment of Keratoconus

Pre- and Post-processing for the Finite Element Model of a CorneaFinal PresentationAdvisor: Craig FosterCivil and Materials EngineeringUniversity of Illinois at Chicago

Graduate Students:Dipika GongalTalisa Mohammad Nejad

Daniel KangLindblom Math and Science Academy

July 21, 2011

http://www.shorelinevision.com/sitepage.asp?page=corneaBackground

Keratoconic corneaHealthy corneahttp://bryanking.net/keratoconus-a-degenerative-disorder/http://1.bp.blogspot.com/_Hxm5RIeMVk8/SpEXpLfplFI/AAAAAAAAGJg/W6SRmkNcnKs/s1600-h/CORNEA

Cornea is the part of the eye that focuses the light. If the shape is somehow distorted, detrimental effects to vision occur. (Interestingly, the cornea is the only part of the human body that does not have blood flowing to it. As such, corneal transplants are somewhat easier to find matches for.)In keratoconus, the structure of the cornea begins to weaken, due to as-yet-unknown reasons. This causes the cornea to deform outwards, which can cause multiple images to appear, due to the poor focusing of the cornea.2Treatment Collagen Crosslinking

Stromahttp://www.nkcf.org/en/treatment-options/corneal-crosslinking/70-corneal-collagen-crosslinking.htmlhttp://www.infobarrel.com/Ultaviolet_Germicidal_Lights_and_Mold_Removal%3A_An_effective_requirement_for_your_Battle_against_Mold

Riboflavin (Vitamin B2)

Two current treatments successfully stop the progression of keratoconus: corneal transplant and collagen crosslinking. The process that we are currently helping to research is the crosslinking, as this avoids complications of transplants (much longer recovery time). 3Finite Element Analysishttp://www.youtube.com/watch?v=7HfMaJJlxTE

Analogy: Rube Goldberg machine? Or dominos? Poking a bowl of Jello can predict its movements. Domino analogy doesnt work too well because of semi-predictability of the arrangement. Then again, some of FEA is also somewhat predictable we should be able to see if the general process is correct or not.

4Model of Human Cornea

Three-Dimensional Modeling and Computational Analysis of the Human Cornea Considering Distributed Collagen Fibril Orientations. Pandolfi, A. and Holzapfel, G. Journal of Biomechanical Engineering. Dec. 2008, Vol. 130. 061006-1-12.This is the 8 parameter-variable equation used to construct the geometric model we are currently working with.5Pre-processingInclusion of different parameters geometric as well as material properties

Refinement

Trade-offs between quality and speedAdd video of me creating an approximation of the mesh of the cornea from scratch.Inclusion of different parameters geometric as well as material properties.Nail-clipping analogy just three clips? Or take more time to file nails as well (go to nail shop)? Depends on level of accuracy/detail required.7ProcessingMatlab computationally the most expensive part

But visually, the most boring part.8Post-processingVisualization of physical conditionsWhat causes the spiraling seen in cornea?

Bron AJ (1973) Vortex patterns of the corneal epithelium. Trans Ophthamol Soc U K 93: 455-472.Almost all human corneas have a clockwise spiral. Mice were seen to have both clockwise and counter-clockwise, w/ some have no spirals at all.9Stress and StrainCompressiveTensileShearhttp://www.youtube.com/watch?v=3pP48_CcDls&NR=1

Work CompletedLearning pre-processing softwareWas not able to obtain experimental data for pre-processing

Studied programming

Worked on post-processingMatlabParaviewSpecial ThanksProf. Andreas LinningerProf. Craig FosterTalisa Mohammad Nejad, Dipika Gongal, Bingqing WangUniversity of Illinois at ChicagoNSF