RETINAL NERVE FIBER LAYER REFLECTANCE MECHANISMS

描述(申请人提供)：青光眼的诊断和治疗需要灵敏的方法来检测和测量视网膜神经节细胞及其轴突的损伤。光学评估视网膜神经纤维层(RNFL)的新的定量方法已经开始提供比以前的方法更高的敏感性和客观性，并正在走向常规的临床应用。这一延续项目的长期目标是a)提供对RNFL的光学特性的全面、定量的基本了解，以及b)将这些基本知识转化为青光眼损害的临床评估的实际改进。 成像微偏振仪、扫描激光偏振仪和光学相干层析成像将用于实现以下具体目标： 1)通过表征RNFL的物理和生物特性，确定对RNFL的光学特性负责的圆柱形结构。RNFL表现为嵌入在双折射平板中的近似平行的光散射柱的均匀厚阵列。反射光谱表明有两种圆柱形机制，一种相对于波长较薄，另一种较厚。圆柱体的身份和RNFL双折射的机制将被确定。 2)对RNFL双折射与神经纤维束结构关系的三种假说进行了体外实验。 3)测量和绘制RNFL的双折射图，为RNFL的“组织诊断”奠定基础。双折射是组织的一种固有属性，直接依赖于RNFL的超微结构，并可能提供一种早期发现青光眼神经节细胞结构损伤的手段。

DESCRIPTION (provided by applicant): The diagnosis and management of glaucoma require sensitive methods for detecting and measuring damage to retinal ganglion cells and their axons. New quantitative methods for optically assessing the retinal nerve fiber layer (RNFL) have begun to deliver enhanced sensitivity and objectivity over previous methods and are moving toward routine clinical use. The long-term objectives of this continuation project are a) to provide a comprehensive, quantitative, basic understanding of the optical properties of the RNFL and b) to translate this basic knowledge into practical improvements in clinical assessment of glaucomatous damage. Imaging micropolarimetry, scanning laser polarimetry and optical coherence tomography will be used to pursue the following Specific Aims: 1) Identify the cylindrical structures responsible for the optical properties of the RNFL by characterizing their physical and biological properties. The RNFL behaves as a uniform thick array of approximately parallel light scattering cylinders embedded in a birefringent slab. Reflectance spectra suggest two cylindrical mechanisms, one thin relative to the wavelength and the other thicker. The identities of the cylinders and the mechanism for RNFL birefringence will be determined. 2) Test in vitro three hypotheses about the relation between RNFL birefringence and the structure of nerve fiber bundles. 3) Measure and map RNFL birefringence in humans as a basis for "tissue diagnosis" of the RNFL. Birefringence is an intrinsic property of the tissue, depends directly on RNFL ultrastructure, and may provide a means of early detection of structural damage to ganglion cells in glaucoma.