Taylor Zachary D, Garritano James, Sung Shijun, Bajwa Neha, Bennett David B, Nowroozi Bryan, Tewari Priyamvada, Sayre James, Hubschman Jean-Pierre, Deng Sophie, Brown Elliott R, Grundfest Warren S
Department of Bioengineering, University of California (UCLA), Los Angeles, CA 90095 USA, and also with the Center for Advanced Surgical and Interventional Technology (CASIT), University of California (UCLA), Los Angeles, CA 90095 USA.
Department of Electrical Engineering, University of California (UCLA), Los Angeles, CA 90095 USA.
IEEE Trans Terahertz Sci Technol. 2015 Mar;5(2):170-183. doi: 10.1109/TTHZ.2015.2392619.
Terahertz (THz) spectral properties of human cornea are explored as a function of central corneal thickness (CCT) and corneal water content, and the clinical utility of THz-based corneal water content sensing is discussed. Three candidate corneal tissue water content (CTWC) perturbations, based on corneal physiology, are investigated that affect the axial water distribution and total thickness. The THz frequency reflectivity properties of the three CTWC perturbations were simulated and explored with varying system center frequency and bandwidths (Q-factors). The modeling showed that at effective optical path lengths on the order of a wavelength the cornea presents a lossy etalon bordered by air at the anterior and the aqueous humor at the posterior. The simulated standing wave peak-to-valley ratio is pronounced at lower frequencies and its effect on acquired data can be modulated by adjusting the bandwidth of the sensing system. These observations are supported with experimental spectroscopic data. The results suggest that knowledge of corneal thickness can be utilized for accurate assessments of corneal tissue water content. The physiologic variation of corneal thickness with respect to the wavelengths spanned by the THz band is extremely limited compared to all other structures in the body making CTWC sensing unique amongst all proposed applications of THz medical imaging.
研究了人角膜的太赫兹（THz）光谱特性与中央角膜厚度（CCT）和角膜含水量的关系，并讨论了基于太赫兹的角膜含水量传感的临床应用价值。基于角膜生理学，研究了三种影响轴向水分分布和总厚度的角膜组织含水量（CTWC）扰动。利用不同的系统中心频率和带宽（品质因数）对三种CTWC扰动的太赫兹频率反射特性进行了模拟和研究。建模结果表明，在有效光程长度为波长量级时，角膜呈现出一个有损耗的标准具，其前部由空气界定，后部由房水界定。模拟的驻波峰谷比在较低频率下较为明显，并且可以通过调整传感系统的带宽来调制其对采集数据的影响。这些观察结果得到了实验光谱数据的支持。结果表明，角膜厚度的信息可用于准确评估角膜组织含水量。与身体中的所有其他结构相比，角膜厚度相对于太赫兹波段所跨越波长的生理变化极其有限，这使得CTWC传感在太赫兹医学成像的所有提议应用中独具特色。
