April 17
@
12:00 PM
–
1:00 PM
Biomechanics of the Optic Nerve Head and Applications to Glaucoma
Thao (Vicky) Nguyen, PhD
Professor and Marlin U. Zimmerman Faculty Scholar
Mechanical Engineering
Johns Hopkins University
Abstract:
The optic nerve head is a small region in the posterior eyewall, where the axons of the retinal ganglion cells gather to exit the eye and form the optic nerve. The lamina cribrosa is a connective tissue structure in the optic nerve head composed of a stack of perforated plates that resemble a collagen beam network structure when viewed en face. The collagen beams support resident astrocytes and axons of the retinal ganglion cells as they exit the eye. Variations in the mechanical properties of the lamina cribrosa may contribute to the susceptibility and progression of glaucoma. Mouse models of glaucoma have been used to study the biomechanical effects of glaucomatous axon damage. The mouse optic nerve head does not have a connective tissue lamina cribrosa. It contains instead a network of astrocytes with long processes organized into structures that are evocative of the collagen beam structure of the human lamina cribrosa. In this presentation, I will describe our efforts to understand the structure-properties relationship of the optic nerve head tissues of human and mouse eyes. We developed ex-vivo inflation tests with optical imaging and 3D digital image correlation (3D-DIC) to measure the mechanical behavior of the lamina cribrosa and astrocytic lamina under physiological conditions. We also developed methods to quantitatively characterize the beam/pore network microstructure of the lamina cribrosa and astrocytic lamina. This has led to a greater understanding of how the lamina structures remodel with glaucoma.
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