A Computational Framework to Determine the Mechanical Properties of Ocular Tissues and a Parametric Study on their Effects on the Biomechanical Response of Lamina Cribrosa

Persistent Link:
http://hdl.handle.net/10150/594913
Title:
A Computational Framework to Determine the Mechanical Properties of Ocular Tissues and a Parametric Study on their Effects on the Biomechanical Response of Lamina Cribrosa
Author:
Ayyalasomayajula, Avinash
Issue Date:
2015
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release 10-Jun-2016
Abstract:
As is the case with many ocular neuropathies, primary open-angle glaucoma (POAG) leads to an irreversible damage to the visual field. Loss of visual field first occurs in the peripheral vision and slowly propagates towards the middle. Although there are differences in its rate of incidence, glaucoma is projected to be the leading cause of blindness, second only to cataract, affecting significant percentage of populations across different age, race/ethnic groups. A hallmark of POAG is the dysfunction of retinal ganglion cells (RGCs) which connect to the axons which, in turn, relay the visual information from the eye to the brain. Previous research has shown that axonal density in the optic nerve head (ONH) is greatly reduced due to chronically elevated intraocular pressure (IOP). IOP-lowering treatment has been shown to reduce the visual field loss, and continues to be the dominant treatment methodology for glaucoma. Previous research has shown that the biomechanics of the lamina cribrosa (LC) - a highly porous tissue through which the axons carrying the visual information exit the eye, is important in influencing the viability of the RGCs. In a normal eye, the LC is primarily made up of collagen of types I, III, and IV which encompass (specifically, arranged circularly) the axon shafts and the blood vessels (1). In addition to elevated IOP, changes in the material properties of ocular tissues in and around the ONH region, which include peripapillary sclera and LC, could affect its biomechanics, which could be a result of changing microstructure and morphology of these tissues, and may contribute to POAG. The current work is aimed at creating computational models to incorporate the complex nature of ocular tissues, and develop computational techniques to characterize the variation in the material properties of ocular tissues (which include the tissue moduli, fiber orientation, permeability etc.), and study the effects they have on the biomechanical response of the LC region.
Type:
text; Electronic Dissertation
Keywords:
glaucoma; inverse mechanics; permeability; porohyperelasticity; sclera; Mechanical Engineering; anisotropy
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Mechanical Engineering
Degree Grantor:
University of Arizona
Advisor:
Vande Geest, Jonathan P.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleA Computational Framework to Determine the Mechanical Properties of Ocular Tissues and a Parametric Study on their Effects on the Biomechanical Response of Lamina Cribrosaen_US
dc.creatorAyyalasomayajula, Avinashen
dc.contributor.authorAyyalasomayajula, Avinashen
dc.date.issued2015en
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.releaseRelease 10-Jun-2016en
dc.description.abstractAs is the case with many ocular neuropathies, primary open-angle glaucoma (POAG) leads to an irreversible damage to the visual field. Loss of visual field first occurs in the peripheral vision and slowly propagates towards the middle. Although there are differences in its rate of incidence, glaucoma is projected to be the leading cause of blindness, second only to cataract, affecting significant percentage of populations across different age, race/ethnic groups. A hallmark of POAG is the dysfunction of retinal ganglion cells (RGCs) which connect to the axons which, in turn, relay the visual information from the eye to the brain. Previous research has shown that axonal density in the optic nerve head (ONH) is greatly reduced due to chronically elevated intraocular pressure (IOP). IOP-lowering treatment has been shown to reduce the visual field loss, and continues to be the dominant treatment methodology for glaucoma. Previous research has shown that the biomechanics of the lamina cribrosa (LC) - a highly porous tissue through which the axons carrying the visual information exit the eye, is important in influencing the viability of the RGCs. In a normal eye, the LC is primarily made up of collagen of types I, III, and IV which encompass (specifically, arranged circularly) the axon shafts and the blood vessels (1). In addition to elevated IOP, changes in the material properties of ocular tissues in and around the ONH region, which include peripapillary sclera and LC, could affect its biomechanics, which could be a result of changing microstructure and morphology of these tissues, and may contribute to POAG. The current work is aimed at creating computational models to incorporate the complex nature of ocular tissues, and develop computational techniques to characterize the variation in the material properties of ocular tissues (which include the tissue moduli, fiber orientation, permeability etc.), and study the effects they have on the biomechanical response of the LC region.en
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectglaucomaen
dc.subjectinverse mechanicsen
dc.subjectpermeabilityen
dc.subjectporohyperelasticityen
dc.subjectscleraen
dc.subjectMechanical Engineeringen
dc.subjectanisotropyen
thesis.degree.namePh.D.en
thesis.degree.leveldoctoralen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineMechanical Engineeringen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorVande Geest, Jonathan P.en
dc.contributor.committeememberVande Geest, Jonathan P.en
dc.contributor.committeememberDeymier, Pierreen
dc.contributor.committeememberMissoum, Samyen
dc.contributor.committeememberWu, Xiaoyien
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