title: THz and mm-Wave Sensing of Corneal Tissue Water Content: Electromagnetic Modeling and Analysis.
abstract: 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 thata prioriknowledge 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.
authors: 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.
authors: Zachary D
authors: ZD
authors: Taylor
authors: 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.
authors: James
authors: J
authors: Garritano
authors: Department of Electrical Engineering, University of California (UCLA), Los Angeles, CA 90095 USA.
authors: Shijun
authors: S
authors: Sung
authors: 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.
authors: Neha
authors: N
authors: Bajwa
authors: Department of Electrical Engineering, University of California (UCLA), Los Angeles, CA 90095 USA. He is now with Fitbit, San Francisco, CA 94105 USA.
authors: David B
authors: DB
authors: Bennett
authors: 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. He is now with Mimeo Labs Inc, Santa Monica, CA 90404 USA.
authors: Bryan
authors: B
authors: Nowroozi
authors: 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. She is now with Elsevier Life Science solutions, San Francisco, CA 94105 USA.
authors: Priyamvada
authors: P
authors: Tewari
authors: Department of Biostatistics, University of California (UCLA), Los Angeles, CA 90095 USA.
authors: James
authors: J
authors: Sayre
authors: Department of Ophthalmology, University of California (UCLA), Los Angeles, CA 90095 USA.
authors: Jean-Pierre
authors: JP
authors: Hubschman
authors: Department of Ophthalmology, University of California (UCLA), Los Angeles, CA 90095 USA.
authors: Sophie
authors: S
authors: Deng
authors: Department. of Electrical Engineering, Wright State University, Dayton, OH 45435 USA.
authors: Elliott R
authors: ER
authors: Brown
authors: 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.
authors: Warren S
authors: WS
authors: Grundfest
keywords: Biological and medical imaging; clinical instruments; hydration interactions; medical diagnostics