基于压平和3-D DIC的角膜生物力学性能活体检测方法及技术研究

A precise measurement of the biomechanical properties of the ocular cornea, such as the stress, strain, stress relaxation, elasticity modulus, hysteresis and ocular rigidity , is very important not only in the guiding and evaluation of the laser corneal refractive surgery for myopia but also in the diagnosis and treatment about the glaucoma and corneal diseases.These inspection technologies of the biomechanical properties measurement in vitro,such as the corneal extension testing, the corneal inflation testing , the optical interferometry , and the whole ocular eyeball perfusion testing, cannot effectively achieve the biomechanical parameter measurement in vivo ,because they destroyed the physiological environment and the intrinsic structure of the cornea .Therefore, it is necessary to develop a non-invasive inspection technology for the measurement of the corneal biomechanical properties in vivo.In this application,several inspection techniques, aimed to achieve the in vivo measurement of the biomechanical parameters of the ocular cornea,are investigated in detailed.For the purpose of real-time detecting the applanation area, displacement and the force exerted to the cornea during applanation tonometry,a new method has been investigated.Based on the method,a new applanation technique for measuring the elasticity modulus,creep and hysteresis behavior of the ocular cornea in vivo is proposed and further a new inspection technology of the ocular rigidity measurement in vivo is investigated.Applications of the three-dimensional digital image correlation (3-D DIC) method for the determination of the biomechanical behavior of the ocular cornea under the inflation conditions are investigated. Using 3D-DIC the full-field displacements on the surface of the corneal sample are calculated and the biomechanical behavior of the ocular cornea,such as creep, hysteresis and stress relaxation, is also tested.Based on these results, the mechanism of ocular cornea deformation under the physiological environment is fully understood ,the laser corneal refractive surgery can be best planned,and intraocular pressure measurement errors with Goldmann applanation tonometer may be corrected. In conclusion,the research results on this project are exceedingly valuable for the clinical practice.

精确测量角膜生物力学性能对近视眼准分子激光角膜屈光手术指导评估和青光眼诊治具有重要作用。现有的检测方法如角膜拉伸法、膨胀法和光学干涉法等，由于采用的技术大多是对角膜进行离体测量，因而不能真实反映活体角膜的生物力学性能。为此，本项目拟开展角膜生物力学性能活体检测方法和技术研究。首先从眼科临床采用的压平式眼压检测方法出发，研究一种能实时同步检测角膜变形压平力、压平面积和压平位移的角膜变形压平式眼压测量新方法；然后发展研究角膜弹性模量、眼壁硬度、蠕变与滞后等力学性能压平式活体检测方法；最后开展三维数字图像相关（3-D DIC）在角膜生物力学性能活体非接触全场光学检测方面的应用技术研究，完成对角膜变形、应变及蠕变、滞后和松弛性能的系统研究，丰富角膜生物力学性能活体检测内容与检测手段。项目研究工作对活体眼角膜变形机制理解、近视眼屈光手术计划和Goldmann眼压测量值误差修正具有重要理论和实际意义。

精确测量角膜生物力学性能对近视眼准分子激光角膜屈光手术指导评估和青光眼诊治具有重要作用。现有的检测方法如角膜拉伸法、膨胀法和光学干涉法等，由于采用的技术大多是对角膜进行离体测量，因而不能真实反映活体角膜的生物力学性能。. 项目完成活体角膜生物力学性能压平与3-D DIC非破坏性全场检测有关理论和关键技术实现。 . 1）完成实时同步检测的角膜变形压平式眼压测量方法及角膜生物力学性能活体压平法检测方法和实验装置研究。项目从眼科临床广泛采用的非侵害性压平式眼内压检测方法出发，提出并实现一种能实时同步检测角膜变形压平力、压平面积和角膜变形压平位移的角膜变形压平式眼压测量方法，搭建实验装置，完成眼内压以及角膜弹性模量、眼壁硬度、角膜蠕变、滞后、松弛等生物力学性能的压平法活体测量，极大地发展压平式眼压检测技术的应用范围。 . 2）实现角膜生物力学性能活体 3-D DIC非接触全场光学测量方法与实验技术装置研究。数字图像相关方法是一种非接触全场光学检测方法，通过比较变形前后物体表面的两幅数字图像而直接获得物体位移和应变信息。项目引入三维数字图像相关（3-D DIC）方法，研究点云拼接技术及图像处理方法，搭建实验装置，通过采用阶跃加载的方式实现角膜变形、应变及角膜的蠕变、滞后和松弛等生物力学性能的活体 3-D DIC 非接触全场光学测量，丰富和发展角膜生物力学性能活体检测手段与检测内容，增加了人们对生理环境下活体眼角膜变形机制的理解。. 3）项目另外开展了基于谱域OCT的气体压陷 (AIOCT) 实验装置研究，进一步用于对角膜生物力学性能进行量化评估，可为圆锥角膜疑似病例的临床诊断等提供一种非侵入和非接触性的检查手段。. 研究工作对眼科临床医师来说意义重大，提供活体眼角膜的生物力学性能测量方法及手段，对生理环境角膜变形机制的理解以及近视眼角膜屈光手术计划和眼压测量值误差修正研究具有重要价值，相应检测技术在眼科临床具有广泛应用前景。