眼角膜生物力学性能非破坏性检测技术研究

发布时间：2018-02-05 22:25

本文关键词： 眼角膜生物力学性能非破坏性测试压平法三维数字图像相关方法　出处：《合肥工业大学》2012年博士论文　论文类型：学位论文

【摘要】：精确测量角膜的生物力学性能如应力、应变、应力松弛、弹性模量、迟滞和蠕变性能以及眼壁硬度等在眼科临床对指导近视眼准分子激光角膜屈光手术、青光眼及角膜疾病的诊治等具有广泛的参考和应用价值。现有的一些角膜生物力学特性检测方法如角膜拉伸法、角膜膨胀法、光学干涉法以及整个眼球的灌注测试法等,由于都是对角膜进行离体测量,破坏了角膜固有的生理环境和结构特征,因而这些技术都不能真实反映角膜的在体生物力学性能。眼反应仪虽然可以实现角膜滞后和阻力特性的在体测量,但是由于没有建立与经典角膜力学参量如弹性模量、应力和应变等的定量关系,在眼科临床的实践中也缺乏具体的指导作用。因此,开展在体非破坏性的角膜生物力学性能检测技术与有关理论和应用研究,具有重要现实意义。本论文工作是在安徽省自然科学研究项目“眼角膜生物力学特性在体测量方法及实验研究”(11040606M128)和安徽省教育厅自然科学基金项目“角膜组织生物力学性能在体非破坏性检测技术与应用研究”(KJ2011z060)的支持下进行的,论文对角膜生物力学性能非破坏性检测方法及关键技术进行了深入的研究。 (1)介绍了传统的压平和压陷眼压检测及最近发展的新型眼眼压测量技术中有关角膜变形的检测方法。重点研究了压平式眼压计工作原理及其在角膜变形检测中的应用,压平式眼压测量技术对在体角膜变形检测具有非损害、测量速度快和精度高等优点。对角膜组织的几何结构、材料和生物力学性能等参量与眼压的关系进行了全面分析,研究一种可同时动态连续在体测量角膜变形压平面积、角膜压平力和角膜变形压平位移的角膜变形压平眼压式测量新方法。研究角膜压平力测量和角膜变形压平面积或位移测量的关键技术,并构建新型角膜变形压平眼压式实验检测装置,最后与“金标准”Goldmann压平式眼压计进行了眼压对比实验研究。结果表明,两者测量值有很好的一致性,证明角膜变形压平式眼压检测装置在压平式眼压测量时可以实现对角膜变形压平的面积、角膜压平力、眼压与角膜变形压平位移同时动态在体检测。 (2)依据压平式眼压测量时眼角膜受力与变形情况分析,采用角膜壳体模型从理论上推导出角膜的弹性模量与角膜变形压平面积、眼压测量值及真正眼内压之间的定量关系,并研究角膜弹性模量压平式检测方法。通过角膜变形压平眼压式测量装置,对角膜材料的弹性模量和蠕变力学行为进行了实验研究。结果表明,角膜弹性模量压平式检测方法可以对角膜的弹性模量及角膜黏弹力学蠕变行为进行有效地非破坏性检测。 (3)研究了角膜变形压平位移、压平力和眼壁硬度的关系,以及眼壁硬度在体压平法检测技术。利用角膜变形压平眼压式测量装置对不同眼球在不同眼压下的角膜压平力及角膜变形压平位移进行了实验检测。初步研究结果表明在相同的角膜变形压平面积时,眼球呈现不同的压平力-压平位移曲线,该技术可以实现“个体化”人眼壁硬度在体非破坏性测量。 (4)数字图像相关方法是一种非接触全场光学检测方法,具有光路简单、量程局限小、全场测量等优点,非常适合生物软组织力学性能测量。研究基于双目立体视觉的三维数字图像相关方法(3-D Digital Image Correlation,3-D DIC)测量的一些基本理论与技术实现,利用电子万能试验机,分别以不同速率对软管生理盐水液柱高度进行线性控制，模拟在体眼内压的变化,采用三维数字图像相关方法对不同眼内压载荷情形下的角膜变形情况进行非接触和非破坏性的全场测量,对角膜变形及角膜的蠕变、滞后和松弛等生物力学行为进行了系统实验研究。结果表明采用3-D DIC方法可以完成角膜生物力学性能非破坏性检测。 (5)角膜是黏弹性材料,同一角膜其弹性模量会随荷载的变化而稍显不同,利用拉伸装置对角膜进行拉伸的同时,采用3-D DIC等光学检测方法虽然可以用来进行离体角膜应力检测,但由于拉伸角膜具有破坏性,因而该技术不能真实检测角膜的力学性能,不具有实用性。采用结构力学中的壳体模型对角膜进行假设,基于薄膜理论的应用,给出一个简单的只采用3-D DIC方法即可完成角膜表面应力检测的新方法。通过角膜膨胀实验,研究结果表明，利用3-D DIC采集的角膜变形位移数据能够实现对模拟眼角膜在眼内压作用下的径向和环向应力分布进行非破坏性检测。
[Abstract]:It is important to accurately measure the biological mechanical properties of cornea such as stress , strain , stress relaxation , elastic modulus , hysteresis , creep property and ocular wall hardness . The work of this paper is carried out under the support of the research on corneal biomechanics in Anhui Natural Science Research Project ( 11040606M128 ) and the Natural Science Foundation of Anhui Provincial Education Department ( KJ2011z060 ) . The non - destructive testing methods and key technologies of corneal biomechanical properties are studied in depth . ( 1 ) A new method for measuring corneal deformation is introduced in this paper , which is based on the principle of appli - tional tonometry and its application in the detection of corneal deformation . ( 2 ) Based on the analysis of the stress and deformation of the cornea when the intraocular pressure is measured , the corneal shell model is used to derive the quantitative relationship between the elastic modulus of the cornea and the corneal deformation , the intraocular pressure measurement and the true intraocular pressure . The elastic modulus and creep mechanics behavior of the corneal material are studied experimentally . The results show that the elastic modulus of the cornea can be effectively nondestructive testing of the elastic modulus and the creep behavior of the cornea . ( 3 ) To study the relationship between corneal deformation , appling force and hardness of the eye wall , and the measurement of the hardness of the eye wall in vivo . The results show that the corneal appling force and the corneal deformation flattening displacement of different eyeball under different intraocular pressure can be measured by using the corneal deformation flattening intraocular pressure measuring device . The results show that the eyeball has different appling force - flattening displacement curve when the same corneal deformation is flattened area , and the technique can realize the non - destructive measurement of the hardness of the human eye wall in the individual . ( 4 ) The digital image correlation method is a non - contact all - field optical detection method , which has the advantages of simple optical path , small measuring range , full field measurement and the like , and is suitable for the measurement of the mechanical property of the biological soft tissue . ( 5 ) The cornea is a viscoelastic material , and the elastic modulus of the same cornea is slightly different depending on the change of the load . While the cornea is stretched by the stretching device , the technique can not truly detect the mechanical property of the cornea , but it is not practical . The experimental results show that the corneal deformation displacement data acquired by the 3 - D DIC can realize nondestructive testing of the radial and circumferential stress distribution of the simulated cornea under the action of intraocular pressure .

【学位授予单位】：合肥工业大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：TH786;R318.01

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