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In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain OCT and an efficient delay estimator

机译：使用光谱域OCT和有效的延迟估计器进行体内泪膜厚度测量和泪膜动力学可视化

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摘要

Dry eye syndrome is a highly prevalent disease of the ocular surface characterized by an instability of the tear film. Traditional methods used for the evaluation of tear film stability are invasive or show limited repeatability. Here we propose a new noninvasive approach to measure tear film thickness using an efficient delay estimator and ultrahigh resolution spectral domain OCT. Silicon wafer phantoms with layers of known thickness and group index were used to validate the estimator-based thickness measurement. A theoretical analysis of the fundamental limit of the precision of the estimator is presented and the analytical expression of the Cramer-Rao lower bound (CRLB), which is the minimum variance that may be achieved by any unbiased estimator, is derived. The performance of the estimator against noise was investigated using simulations. We found that the proposed estimator reaches the CRLB associated with the OCT amplitude signal. The technique was applied in vivo in healthy subjects and dry eye patients. Series of tear film thickness maps were generated, allowing for the visualization of tear film dynamics. Our results show that the central tear film thickness precisely measured in vivo with a coefficient of variation of about 0.65% and that repeatable tear film dynamics can be observed. The presented method has the potential of being an alternative to breakup time measurements (BUT) and could be used in clinical setting to study patients with dry eye disease and monitor their treatments.
机译：干眼综合征是眼表疾病的高度流行，其特征是泪膜不稳定。用于评估泪膜稳定性的传统方法是侵入性的或显示出有限的可重复性。在这里，我们提出了一种使用有效延迟估计器和超高分辨率光谱域OCT来测量泪膜厚度的新的非侵入性方法。具有已知厚度和组指数的层的硅晶片模型用于验证基于估计器的厚度测量。给出了估计器精度的基本极限的理论分析，并推导了Cramer-Rao下界（CRLB）的分析表达式，该表达式是任何无偏估计器均可实现的最小方差。使用仿真研究了估计器针对噪声的性能。我们发现，提出的估计器达到了与OCT幅度信号相关的CRLB。该技术已在体内应用于健康受试者和干眼症患者。生成了一系列的泪膜厚度图，从而可以可视化泪膜动力学。我们的结果表明，在体内精确测量的中央泪膜厚度具有约0.65％的变化系数，并且可以观察到可重复的泪膜动力学。提出的方法有可能替代分手时间测量（BUT），可用于临床研究患有干眼症的患者并监测其治疗。

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  • 来源
    《》|2016年|969706.1-969706.11|共11页
  • 会议地点 San Francisco CA(US)
  • 作者

    Valentin Aranha dos Santos; Leopold Schmetterer; Martin Groeschl; Gerhard Garhofer; Rene M. Werkmeister;

  • 作者单位

    Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna, Austria,Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

    Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna, Austria,Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20/6L, A-1090 Vienna, Austria;

    Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

    Department of Clinical Pharmacology, Medical University of Vienna, Waehringer Guertel 18-20/6L, A-1090 Vienna, Austria;

    Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, A-1090 Vienna, Austria;

  • 会议组织
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Tear film; dry eye; delay estimator; Cramer-Rao lower bound;

    机译：泪膜;眼干延迟估计器Cramer-Rao下界;

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