膨胀试验测定猪眼角膜生物力学参数的研究

Determining the ex vivo biomechanical properties of porcine cornea with inflation test

目的通过膨胀试验测定猪眼角膜的非线性应力/应变关系,研究猪眼角膜弹性模量和眼内压之间的关系。方法选取新鲜猪眼11只,剪下附带4～5 mm宽度巩膜环的角膜,采取胶水黏附联合机械固定方式将猪眼角膜固定于自制的施压装置,缓慢逐步增加液压,液压范围:0.244～9.776 kPa,激光位移计记录角膜前表面顶点的前突位移量,根据板壳理论推导公式计算猪眼角膜的生物力学参数,包括应力、应变及弹性模量。结果猪眼角膜前突位移量同眼内压的关系及应力/应变均呈指数函数关系,弹性模量与眼内压呈线性关系。结论膨胀法测量猪眼角膜的弹性模量具有较好的重复性和精确性,此方法所测得的弹性模量可用于后期屈光手术模型的建立、人工角膜与角膜接触镜设计及其他方面的研究。

Objective Objective To determine the biomechanical behavior of porcine cornea and establish the relationship between the elastic modulus and intraocular pressure （IOP）. Method Eleven fresh porcine corneal specimens were examined under inflation conditions to determine the constitutive relationships of the material through static loading conditions （pressure range： 0244 -9.776 kPa）. The forward deflection of porcine anterior corneal apex was measured by the laser displacement sensor. The pressure-deformation results were analyzed on the basis of shell theory to estimate elastic modulus of the cornea and derive its relationship with lOP. Result The porcine corneas showed a nonlinear corneal forward displacement/IOP and stress/strain relationship with an initial low stiffness stage and a later high stiffness stage. In spite of the nonlinearity between the internal pressure and apexforward deflection, the relationship between the elastic modulus and the IOP was almost linear. Condusions This inflation configuration can be used to estimate the mechanical property of corneas, and the resulted material parameters could be applied to numerical simulations of refractive surgery procedures, contact lens fitting, artificial cornea design and other applications.