Age-related changes in optic nerve head structure and biomechanics

描述（由申请人提供）：眼压升高（IOP）一直被认为是造成视神经头（ONH）青光眼损害的原因。患者年龄是青光眼损害发生和进展的最重要危险因素之一，无论青光眼处于哪个阶段或发生青光眼时的眼压（IOP）水平如何。然而，目前尚不清楚IOP是如何引发导致视网膜神经节细胞死亡的一系列事件的。我们假设与年龄相关的ONH生物力学改变对人类老年ONH易感性的增加起重要作用。

DESCRIPTION (provided by applicant): Elevated intraocular pressure (IOP) has long been assumed to play a causative role in glaucomatous damage to the optic nerve head (ONH). Patient age is among the most important risk factors for the onset and progression of glaucomatous damage, regardless of the stage of glaucoma or the level of intraocular pressure (IOP) at which it has occurred. It is still unclear, however, how IOP triggers the cascade of events that lead to retinal ganglion cell death. We hypothesize that age-related alterations in ONH biomechanics contribute importantly to the increased susceptibility of the aged ONH in humans. Using three-dimensional (3D) reconstructions of the ONH, and principles of biomechanical engineering, we have studied the mechanical effects of elevated IOP in glaucoma. However, the relationship between patient age and the mechanical effects of elevated IOP is still unclear. How is the ONH altered as in the older patient that increases its susceptibility to IOP? Is the robustness of the ONH connective tissues the key to understanding individual susceptibility to glaucoma? What role does the structural stiffness of the lamina cribrosa and peripapillary sclera play in the increased age-related risk for glaucomatous progression? To answer these questions, we will use novel methods to elucidate the relationship between age and the IOP- induced deformation of ONH connective tissues are needed. By "ONH biomechanics" we mean the interactions between IOP and connective tissue structural stiffness (the combination of tissue architecture and material properties) in the ONH and peripapillary sclera. The immediate goals of this project are to characterize age-related differences in ONH biomechanics and elucidate their effects on ONH susceptibility. Our long-term goal is to develop clinical diagnostics and interventions designed to manage each important biomechanical risk factor in the development and progression of glaucoma. To accomplish our immediate goals, we will build digital three-dimensional reconstructions of young and old human ONH tissues, quantify the ONH connective tissue architecture within each reconstruction, and build computational finite element models of the ONH connective tissues to estimate their biomechanical response to normal and elevated levels of IOP. We will also correlate the age-related variations in ONH architecture, tissue stiffness, and biomechanical behavior with the increased susceptibility and clinical behavior of the aged ONH. PUBLIC HEALTH RELEVANCE. Elevated intraocular pressure (IOP) has long been assumed to play a causative role in glaucomatous damage to the optic nerve head (ONH), and older patients have higher risk of development and progression of the disease. We propose to measure the age-related differences in ONH structure and IOP-induced biomechanical response. Then, using the principles of biomechanical engineering, we will use these data to create computational models of the age-related mechanical effects of elevated IOP on the ONH to elucidate the link between advancing age and glaucomatous susceptibility.