Huang Jinxin, Yuan Qun, Zhang Buyun, Xu Ke, Tankam Patrice, Clarkson Eric, Kupinski Matthew A, Hindman Holly B, Aquavella James V, Suleski Thomas J, Rolland Jannick P
Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
The Institute of Optics, University of Rochester, Rochester, New York 14627, USA ; School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China.
Biomed Opt Express. 2014 Nov 24;5(12):4374-86. doi: 10.1364/BOE.5.004374. eCollection 2014 Dec 1.
To extend our understanding of tear film dynamics for the management of dry eye disease, we propose a method to optically sense the tear film and estimate simultaneously the thicknesses of the lipid and aqueous layers. The proposed method, SDT-OCT, combines ultra-high axial resolution optical coherence tomography (OCT) and a robust estimator based on statistical decision theory (SDT) to achieve thickness measurements at the nanometer scale. Unlike conventional Fourier-domain OCT where peak detection of layers occurs in Fourier space, in SDT-OCT thickness is estimated using statistical decision theory directly on the raw spectra acquired with the OCT system. In this paper, we demonstrate in simulation that a customized OCT system tailored to ~1 µm axial point spread function (FWHM) in the corneal tissue, combined with the maximum-likelihood estimator, can estimate thicknesses of the nanometer-scale lipid and micron-scale aqueous layers of the tear film, simultaneously, with nanometer precision. This capability was validated in experiments using a physical phantom that consists of two layers of optical coatings that mimic the lipid and aqueous layers of the tear film.
为了扩展我们对用于干眼疾病管理的泪膜动力学的理解，我们提出了一种光学检测泪膜并同时估计脂质层和水液层厚度的方法。所提出的方法，即统计决策理论光学相干断层扫描（SDT-OCT），将超高轴向分辨率光学相干断层扫描（OCT）与基于统计决策理论（SDT）的稳健估计器相结合，以实现纳米级别的厚度测量。与传统的傅里叶域OCT不同，在传统傅里叶域OCT中，层的峰值检测发生在傅里叶空间，而在SDT-OCT中，厚度是直接使用统计决策理论对OCT系统采集的原始光谱进行估计的。在本文中，我们通过模拟证明，定制的OCT系统针对角膜组织中约1 µm轴向点扩散函数（半高宽）进行了优化，并结合最大似然估计器，能够以纳米精度同时估计泪膜的纳米级脂质层和微米级水液层的厚度。这种能力在使用由两层模拟泪膜脂质层和水液层的光学涂层组成的物理模型的实验中得到了验证。
