RETINAL NERVE FIBER LAYER REFLECTANCE MECHANISMS

描述（由申请人提供）：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）的新定量方法已经开始比以前的方法提供更高的灵敏度和客观性，并正在走向常规临床应用。该项目的长期目标是：a)对RNFL的光学特性提供全面、定量、基本的认识；b)将这些基本知识转化为青光眼损伤临床评估的实际改进。

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.