Noninvasive assessment of the cornea by diffusion OCT

圆锥角膜是一种角膜退行性疾病，是视力下降的主要原因。 在美国，生活质量的提高往往会导致角膜移植。屈光手术后的扩张是一种 尽管目前进行了筛查，但明显风险较低的患者仍可能出现威胁视力的并发症 技术角膜的生物力学特性在这些疾病中起着核心作用，但诊断 仍然植根于形状测量，因为医生缺乏对生物力学变化的直接测量。而当 有几种方法已经显示出解决这一差距的早期希望，大多数方法需要接触或干扰 对于角膜，不能在空间上解决生物力学特性，也不能涉及昂贵的光学系统。 为了满足对角膜进行直接生物力学测量的需要以及其他方法的局限性 方法，我们引入了相位去相关OCT(PHD-OCT)。PHD-OCT利用光学相干性 断层扫描(OCT)，以量化随机纳米级的流动性，与强度和凝聚力有关 眼角膜。初步结果有力地支持了该方法的理论基础、可行性和潜在优势。 我们的目标是：(1)改进我们的方法，以优化检测灵敏度和速度，以及(2) 确定这项技术是否在临床上有用。我们将通过以下目标实现这些目标： 1.建立和验证用于角膜成像的运动敏感型PHD-OCT。光谱域OCT将 用于前段相位去相关成像，并对分析算法进行优化。这个 系统将使用模体和扭转流变仪进行验证。 2.研究生理因素(眼压、水合作用、 温度)。在猪和人类供体球体上的析因设计实验将确定 对潜在混杂因素的PHD-OCT测量。 3.开发和验证数据采集和处理方法，以实现临床测试。GPU 将配置处理和机器学习，以最大限度地减少处理时间。扫描模式将是 优化以最大限度地减少扫描时间并返回临床有用的数据。 4.评估临床活动性敏感OCT成像的可行性和初步诊断性能 在眼角膜上。一项首次人类研究将表征重复性，并测试PHD-OCT的假设 活动度测量在LASIK瓣区域增加，在CXL减少。 预期结果：拟议的研究将建立一种新的、非接触式的角膜成像方法 生物力学特性，有可能解决当前和新兴方法的许多缺点。 成功可能导致更早发现扩张症风险，并允许更适当的时机和定制 眼角膜治疗。未来将数据集成到计算模型中可能会产生重大影响 通过推动从经验性规划和风险分析到针对患者的策略的转变，在这一领域开展研究。

Keratoconus is a degenerative disease of the cornea that is a major cause of reduced vision-related quality of life in the United States, often leading to corneal transplantation. Ectasia after refractive surgery is a vision-threatening complication that can occur in apparently low-risk patients despite current screening technology. The biomechanical properties of the cornea play a central role in these diseases, but diagnostics are still rooted in shape measures because doctors lack direct measures of biomechanical change. While several methods have shown early promise for addressing this gap, most require contact with or perturbation of the cornea, cannot spatially resolve biomechanical properties, or involve expensive optical systems. To address the need for direct biomechanical measurement of the cornea and the limitations of other approaches, we introduce phase-decorrelation OCT (phd-OCT). Phd-OCT makes use optical coherence tomography (OCT) to quantify random nanoscale mobility that is related to the strength and cohesion of the cornea. Preliminary results strongly support the rationale, feasibility and potential advantages of the approach. Our objectives are: (1) to refine our method to optimize detection sensitivity and speed, and (2) to determine if the technique is clinically useful. We will achieve these objectives through the following aims: 1. To develop and validate mobility-sensitive phd-OCT for corneal imaging. Spectral-domain OCT will be used for anterior segment phase-decorrelation imaging and the analysis algorithm will be optimized. The system will be validated using phantoms and torsional rheometry. 2. To investigate the potential influence of physiological factors (intraocular pressure (IOP), hydration, and temperature). Factorial design experiments in porcine and human donor globes will establish the sensitivity of phd-OCT measurements to potential confounders. 3. To develop and validate data acquisition and processing methods to enable clinical testing. GPU processing and machine learning will be configured to minimize processing time. Scan patterns will be optimized to minimize scan time and return clinically useful data. 4. To assess feasibility and preliminary diagnostic performance of clinical mobility-sensitive OCT imaging of the cornea. A first-in-human study will characterize repeatability and test the hypotheses that phd-OCT mobility measurements are increased in the region of a LASIK flap and decreased in CXL. Expected Outcomes: The proposed studies will establish a new, non-contact method for imaging corneal biomechanical properties with the potential to address many shortcomings of current and emerging methods. Success could lead to earlier detection of of ectasia risk and allow more appropriate timing and customization of corneal treatments. Future integration of data into computational models has the potential to greatly impact the field by driving a shift from empirical planning and risk analysis to patient-specific strategies.