全眼球一体化分析角巩膜本构参量区域差异性的研究

Numerical simulation of the ocular response to applied forces is of particular interest as it can lead to improvements in diagnosis and treatment of degenerative ocular conditions such as keratoconus and pathological myopia. To provide accurate simulations, full knowledge is required of the ocular material properties , geometry, loading and boundary conditions. Nonlinear and regional variation are two main biomechanical properties of the corneoscleral tissue. Earlier studies attempted to characterise the mechanics of ocular tissue using combinations of uniaxial strip tests, corneal or scleral inflation tests and whole eye globe inflation tests. Among these methods, in-vitro whole globe inflation is the test that most closely represents in-vivo ocular physiological conditions, but so far the test has not been used to its full potential with the use of unrealistic support conditions, lack of consideration of regional variation of behaviour and the restriction of attention to the behaviour of either the cornea or sclera. In this project, whole globe inflation will be used to address a number of fundamental shortfalls associated with earlier test methods through (1) the provision of more realistic supports instead of the fixed-edge conditions commonly used, and (2) consideration of the regional variation of behaviour across the whole ocular surface based on whole globe integrated analysis method. The eye will be loaded with cycles of computer-controlled intraocular pressure, and the behaviour monitored with a set of spatially spaced digital cameras to capture the distribution of deformation across the whole eye surface. An eye-specific numerical model will be built based on the same camera images. Whole globe integrated analysis method and inverse modeling procedure were used to derive the constitutive parameters at different parts of the ocular globe based on the displacements obtained from the digital image correlation procedure. Then a mathematical model will be established to describe the distribution of the constitutive parameters in different ocular regions. The use of low-stiffness gelatine to support the eye during the test provides a similar support to the soft tissue surrounding the in-vivo eye, and prevents drying during the test. Consideration of spatially spaced digital cameras, combining their images and using whole globe integrated analysis method enables the accurate determination of the regional variation of properties. The method, once built and validated, will be used on the eyes of a number of species including humans, pigs and rabbits. The regional variation results of corneoscleral constitutive parameters of the study can be used to improve current understanding of corneal and scleral biomechanical behaviour, the mathematical model incorporating the constitutive parameters will enable a more accurate representation of regional corneal and scleral biomechanics in numerical simulations.

近视及圆锥角膜的发生发展与巩膜及角膜区域性生物力学性能改变密切相关，了解角巩膜生物力学性能的区域分布差异在眼部疾病诊断,眼科手术改进等方面具有重要意义。区域差异性是角巩膜组织的重要生物力学特征，受现有实验平台和分析方法的限制，无法提供全眼球角巩膜生物力学性能的区域差异分布。结合我们前期建立离体角膜膨胀实验平台测量兔眼及猪眼角膜的本构参量，测试和评估各类眼科仪器及实验平台，设计透明软性明胶固定法模拟眼周组织支撑眼球，预实验探索个性化全眼球三维建模、眼球形变信息提取等方法的工作基础。本研究拟从改进实验平台及探索新型分析方法入手，旨在搭建和验证新型离体全眼球膨胀实验平台，探索全眼球一体化分析角巩膜生物力学性能的方法，探讨和分析全眼球角巩膜本构参量的区域差异分布，尝试构建描述本构参量区域差异性的数学模型，实现更为可靠与精确地测量眼生物力学性能参数，为角巩膜区域差异性生物力学特征的应用奠定基础。

近视及圆锥角膜的发生发展与巩膜及角膜区域性生物力学性能改变密切相关，了解角巩膜生物力学性能的区域分布差异对眼部疾病诊断，眼科手术改进等方面具有重要意义。区域差异性是角巩膜组织的重要生物力学特征，受现有实验平台和分析方法的限制，无法提供全眼球角巩膜生物力学性能的区域差异分布，本项目在研究方法方面实现了突破。研究内容包含继续拓展离体角膜膨胀实验平台的应用，评估糖尿病对兔眼角膜本构参量的影响；搭建新型离体全眼球膨胀实验平台，改进眼组织厚度测量方法，探索出全眼球一体化分析角巩膜生物力学性能的方法，评估了全眼球角巩膜本构参量的区域差异分布。已在国内外权威期刊上发表6篇论文，申请国家发明专利3项(其中授权1项)，已培养硕士研究生2名、博士研究生1名，在国家级以上会议收录论文及发言7篇。实现较为可靠与精确地测量眼生物力学性能参数，为角巩膜区域差异性生物力学特征的应用奠定基础。

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