Human optic nerve head biomechanics: An analysis of generic and individual-specific models using the finite element method.
Published: 2006
Language: eng
Number of pages: 248
ISBN-13: 9780494219607
Description: Glaucoma is a leading cause of blindness worldwide, yet the etiology of the disease is unclear. A leading hypothesis is that elevated intraocular pressure (IOP) produces an altered biomechanical environment within the tissues of the optic nerve head (ONH) and these biomechanical factors contribute to optic nerve damage and the consequent loss of vision. The range of individual susceptibilities to elevated IOP is believed to be, at least in part, due to differences in ONH anatomy and tissue biomechanical properties.Our objective was to use computational modelling to characterize the biomechanical environment within and around the human ONH, and to evaluate the role of IOP in the development of glaucoma. We present the first individual-specific (IS) models of the human ONH, with geometry based on serial histological sections from donor eyes. We also present generic models based on previously reported ONH morphometric data. The finite element method (FEM) was used to simulate a model's response to changes in IOP. Model response was quantified through a set of outcome measures that included various modes of strain within each of the ONH tissues and several measures of geometry. To determine the degree to which anatomical and biomechanical factors could influence the sensitivity of an ONH to changes in IOP, we also carried out parametric and sensitivity analyses on both generic and IS models.We show that IOP-induced levels of strain within the ONH reach potentially biologically significant levels. Mechanical insult to ONH tissues depends more strongly on tissue biomechanical properties than on the details of the ONH anatomy. In particular, scleral stiffness has a large influence on ONH biomechanics and could therefore be a risk factor for glaucomatous optic neuropathy. Scleral thickness, eye size and lamina cribrosa stiffness are other predicted risk factors. We also found that the mechanical response of an ONH to changes in IOP is complex, and cannot be described by one measure of strain. The largest ONH strains occur in compression, followed by shearing and finally by extension.
Notes: Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0441.

Thesis (Ph.D.)--University of Toronto, 2006.

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