Glaucoma is a leading cause of blindness in the United States, and the second leading cause worldwide. There is consensus that the level of intraocular pressure generates a biomechanical response in the tissues of the optic nerve head that is fundamental to the early events in glaucoma damage. The level and state of stress and strain in the optic nerve head are determined by the mechanical properties of the posterior sclera and lamina cribrosa and how they differ. Mechanical stresses and deformation of the optic nerve head can damage the retinal ganglion cell axons both directly and indirectly through mechanical activation of the lamina cribrosa cells and disruption of blood ?ow from the distortio of blood vessels. We hypothesize that the biomechanical interaction of the sclera and lamina cribrosa is central to the development glaucomatous optic neuropathy. To investigate this hypothesis, we will develop in Aim 1 an innovative microscopic in?ation experiment to measure the local deformation response of the lamina cribrosa of human post-mortem eyes, and examine the effects of scleral behavior measured for the same eye, age, and glaucoma stage.
In Aim 2, we will separate the contributions of the extracellular matrix components by measuring changes to the pressure-induced deformation behavior of the lamina cribrosa cause by chemical modi?cations, either stiffening or softening, of only the sclera or of the sclera and lamina cribrosa. We will measure the collagen and elastin structure of the lamina cribrosa in Aim 3 and evaluate for the effects of the scleral ?ber structure measured for the same eye, age, and glaucoma stage.
Aim 4 will integrate the data gathered from the mechanical and structural experiments in computational models of the lamina cribrosa and sclera to study the relationship between microstructure and mechanical properties of the tissues. The proposed Aims will advance both the fundamental scienti?c understanding of the pathogenesis of glaucoma and the development of new diagnostic and neuroprotection strategies. The outcomes of Aim 1 will provide the physiological and pathological levels of mechanical stimuli to the tissues of the op- tic nerve head for studies of blood ?ow and mechanical activation of lamina cribrosa cells. The outcomes of Aim 2 will measure the effect of selective scleral stiffening or softening on the stresses and strains in the optic nerve head, thus will guide the development of new scleral neuroprotection strategies.
Aims 3 and 4 will provide an understanding of the relationship between the microstructure and mechanical behavior of the lamina cribrosa. This will allow us to predict features that can be identi?ed as biomechanical markers in in vivo optical coherence tomography imaging for new diagnostic strategies. The proposed work will provide the ?rst study of the biomechanics of the lamina cribrosa and the peripapillary sclera in relation to each other in the same eye. It will also provide the ?rst detailed measurements of the effect of selective scleral stiffening and softening on the strain state of the optic nerve head.
Glaucoma is a leading cause of blindness in the United States, and the second leading cause worldwide. This project investigates the role of the biomechanical behavior of the lamina cribrosa in relation to the posterior sclera of the same eye in the development of glaucomatous damage. The implications of this work can be important to understanding the susceptibility of individuals to glaucoma, to developing new diagnostic techniques based on biomechanical interpretations of advanced in vivo imaging methods, and to developing new neuroprotection strategies, such as chemical treatments that selectively alter the mechanical properties of the sclera and lamina cribrosa or of the peripapillary sclera alone, to halt the progression the disease.
| Midgett, Dan E; Pease, Mary E; Jefferys, Joan L et al. (2017) The pressure-induced deformation response of the human lamina cribrosa: Analysis of regional variations. Acta Biomater 53:123-139 |
| Nguyen, Cathy; Midgett, Dan; Kimball, Elizabeth C et al. (2017) Measuring Deformation in the Mouse Optic Nerve Head and Peripapillary Sclera. Invest Ophthalmol Vis Sci 58:721-733 |
| Murienne, Barbara J; Nguyen, Thao D (2016) A comparison of 2D and 3D digital image correlation for a membrane under inflation. Opt Lasers Eng 77:92-99 |
| Murienne, Barbara J; Chen, Michelle L; Quigley, Harry A et al. (2016) The contribution of glycosaminoglycans to the mechanical behaviour of the posterior human sclera. J R Soc Interface 13: |
| Coudrillier, Baptiste; Pijanka, Jacek; Jefferys, Joan et al. (2015) Effects of age and diabetes on scleral stiffness. J Biomech Eng 137: |
| Murienne, Barbara J; Jefferys, Joan L; Quigley, Harry A et al. (2015) The effects of glycosaminoglycan degradation on the mechanical behavior of the posterior porcine sclera. Acta Biomater 12:195-206 |
| Pijanka, Jacek K; Spang, Martin T; Sorensen, Thomas et al. (2015) Depth-dependent changes in collagen organization in the human peripapillary sclera. PLoS One 10:e0118648 |
| Coudrillier, Baptiste; Pijanka, Jacek; Jefferys, Joan et al. (2015) Collagen structure and mechanical properties of the human sclera: analysis for the effects of age. J Biomech Eng 137:041006 |
| Nguyen, Thao D; Ethier, C Ross (2015) Biomechanical assessment in models of glaucomatous optic neuropathy. Exp Eye Res 141:125-38 |
| Coudrillier, Baptiste; Pijanka, Jacek K; Jefferys, Joan L et al. (2015) Glaucoma-related Changes in the Mechanical Properties and Collagen Micro-architecture of the Human Sclera. PLoS One 10:e0131396 |
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