CONTINUUM-LEVEL FINITE ELEMENT MODELING OF THE OPTIC NERVE HEAD USING A FABRIC TENSOR BASED DESCRIPTION OF THE LAMINA CRIBROSA

摘要

Glaucoma is a chronic disease of the eye that can progress to severe vision impairment or blindness if left untreated. The principal site of glaucomatous damage is believed to be within the optic nerve head (ONH) where the axons of the retinal ganglion cells pass through an opening in the back of the sclera (the eye wall) on their way to form the orbital optic nerve. This opening is spanned by the lamina cribrosa (LC), a fenestrated connective tissue structure which provides both a load bearing function for the eye as well as support (both structural and metabolic) for axonal bundles as they traverse the porous space of the LC. Elevated intraocular pressure (IOP) is often associated with glaucomatous damage, but the mechanism by which increased IOP impairs axonal health is unclear. An emerging paradigm suggests that IOP-related deformation of the LC initiates a cascade of axonal damage that is mediated by a combination of mechanical strain, ischemia, and cellular responses [1]. The purpose of the present study was to explore the biomechanical response of the connective tissues of ONH and posterior scleral shell to IOP using anatomical 3D finite element (FE) models which incorporate characterization of the porous microstructure of the lamina cribrosa into the models' material description.