Wang H, Prendiville P L, McDonnell P J, Chang W V
Department of Chemical Engineering, Doheny Eye Institute, University of Southern California, Los Angeles 90089, USA.
J Biomech. 1996 Dec;29(12):1633-6.
In the hopes of reducing the unpredictability associated with refractive surgical procedures and ultimately improving surgical techniques, many investigators have attempted to determine the elastic moduli of the cornea. Techniques such as stress-strain tests of corneal strips and the measurement of mercury drop displacement in a whole eye under increasing pressure have resulted in a range of values for Young's modulus from 10(5) to 10(7) Nm-2. Both of these methods are limited because these mechanical tests cannot be performed in the physiological state and because of the large amount of force applied during testing. We used an ultrasonic technique to determine the elastic moduli of the human cornea. Two groups of six corneas prepared under different conditions (in saline and in dextran) were examined separately and the shear waves were generated and detected in these 12 human eye bank eyes. All the waveforms were digitized and saved in files of binary format. Fast Fourier transformation (FFT) was applied to calculate the speed and attenuation of the shear wave. Using the resulting wave speeds and attenuation coefficients, the Young's moduli of the corneal samples were calculated as (5.3 +/- 1.1) x 10(6) Nm-2 and (2.0 +/- 1.0) x 10(7) Nm-2 for cornea samples prepared in saline and in dextran at 2.25 MHz, respectively.
为了减少屈光手术的不可预测性并最终改进手术技术，许多研究人员试图测定角膜的弹性模量。诸如角膜条带的应力-应变测试以及在逐渐增加的压力下测量全眼内汞滴位移等技术，得出杨氏模量的值在10⁵至10⁷ Nm⁻²之间。这两种方法都有局限性，因为这些力学测试无法在生理状态下进行，且测试过程中施加的力很大。我们使用超声技术来测定人角膜的弹性模量。分别检查了在不同条件下（在盐溶液和葡聚糖中）制备的两组各六个角膜，并在这12只人眼库眼中产生并检测了剪切波。所有波形都进行了数字化处理并以二进制格式保存到文件中。应用快速傅里叶变换（FFT）来计算剪切波的速度和衰减。利用所得的波速和衰减系数，对于在2.25 MHz下于盐溶液和葡聚糖中制备的角膜样本，计算出的角膜样本杨氏模量分别为(5.3±1.1)×10⁶ Nm⁻²和(2.0±1.0)×10⁷ Nm⁻²。
