基于超声压痕技术的兔眼角膜生物力学特性

Biomechanical properties of rabbit cornea based on ultrasonic indentation

目的利用超声压痕技术探索兔眼角膜的生物力学特性。方法选取7月龄新西兰白兔眼球7只,制作完整角膜试样并固定于人工前房上。用微量注射泵给人工前房注水改变前房内的压力,并用压力传感器测量;在不同前房压力状态下,利用超声压痕设备在角膜顶点位置进行压痕实验,获得力-位移曲线。研究角膜力学参数(弹性模量、滞回量等)与前房压力的关系。结果由角膜压痕实验所得的力-位移曲线呈现非线性特点。前房内压力越大,角膜的力-位移曲线越陡峭。兔眼角膜的弹性模量随前房压力升高而增大,在前房压力为7～45 mm Hg(1 mm Hg=0. 133 k Pa)范围内,其数值范围为0. 30～1. 55 MPa。随前房压力增大,角膜滞回量呈现线性上升趋势。结论基于超声压痕技术获得的兔眼角膜弹性模量随前房压力呈线性增大,滞回量等角膜黏性特性参数与前房压力也相关。

Objective The biomechanical properties of rabbit corneas in vitro were explored by ultrasonic indentation experiment. Metheds Seven eye balls of New Zealand white rabbit with 7-month-old were used and the corneas were fixed on an artificial anterior chamber. The pressure in the anterior chamber were changed by injecting or ejecting normal saline in the artificial anterior chamber by a microinjection pump,and the intraocular pressure in the chamber was measured in real time by a pressure sensor. Indentation experiment was performed on the corneal apex by the ultrasonic indentation device at different pressure states,and the relationships between corneal biomechanical parameters and intraocular pressure were studied. Results The force-displacement curves of cornea in loading and unloading process were nonlinear. The higher the intraocular pressure,the steeper the load-displacement curves. At the intraocular pressure range of 7 mmHg to 45 mmHg,corneal tangent modulus increased with pressure with the value ranging between 0.30 to 1.55 MPa. The amount of hysteresis indicated the energy consumption of the cornea during loading and unloading process,was related to the viscous of the cornea. The result showed that the greater the pressure,the greater the amount of hysteresis would be. Conclusions Ultrasonic indentation experiments show that the corneal tangent modulus increases linearly with intraocular pressure and the viscous parameters are related with intraocular pressure.