兔眼角膜生物力学特性的年龄相关性

目的 利用兔眼角膜条的单轴拉伸实验数据，研究角膜生物力学特性与年龄的相关性。方法 分别取3月龄和7~8月龄兔眼角膜条，实施单轴拉伸实验，获得实验数据；用指数模型和幂模型对应力 应变数据进行分析；用黏弹性力学模型对应力松弛数据进行分析。结果兔眼角膜条呈现非线性黏弹性特征。在实验误差允许的范围内，不同月龄兔眼角膜条的非线性应力-应变关系差别不明显，7~8月龄兔眼角膜的切线模量略偏大，但其应力衰减得明显快。不同的拉伸速率对3月龄兔眼角膜条非线性应力-应变关系的影响不明显，但快速拉伸后的角膜条应力衰减明显变快。结论 兔眼角膜随月龄增加会轻微变硬，而角膜的松弛特性随月龄变化明显。

Age-related changes in biomechanical properties of rabbit corneas

Objective To study the age-related changes in biomechanical properties of rabbit cornea by using the data from uniaxial extension testing on rabbit cornea strips. Methods To obtain the experiment data, the uniaxial extension test on rabbit cornea strips of both 3-month old and 7 to 8 month-old were performed. The exponential function model and power function model were used to fit the strain-stress curves, and two kinds of viscoelastic mechanical models were used to analyze the stress relaxation curves. Results The mechanical behavior of the rabbit cornea strip presented a nonlinear and viscoelastic property. Within the range of error permitting, the age was not an important factor to affect the stress-strain, as no significant difference was found in nonlinear stress-strain curve of rabbit cornea strips between different ages. The cornea strips of 7 to 8 month-old rabbit had a slightly bigger elastic modulus and a faster stress relaxation than those of 3 month-old one. Different stretching rates had no obvious influence on the nonlinear stress-strain of 3-month old rabbit cornea strips, but the cornea strips at high stretching rate could have a faster stress relaxation. Conclusions The tangent modulus of rabbit cornea increases slightly with age, but its relaxation properties would change greatly with age.