RETINAL NERVE FIBER LAYER REFLECTANCE MECHANISMS

青光眼的诊断和治疗需要敏感的方法， 检测和测量视网膜神经纤维的损伤。 新研发 用于光学评估视网膜神经纤维层的定量方法 （RNFL）承诺提高敏感性和客观性，但更基本 需要知识来解释和改进它们。 这项研究的长期目标是提供一个全面的 RNFL的光学性质的定量描述，以及 为它的反射率建立解剖学基础。 蟾蜍视网膜的实验表明，RNFL反射率来自于 均匀分布的圆柱形结构。 一个新的理论模型 根据神经纤维束的超微结构， 膜的反射率占主导地位，但初步实验表明， RNFL反射率的很大一部分来自于 微管 该模型预测，膜和微管机制 在偏振光下会有不同的表现 该项目的具体目标是： 1)对大鼠RNFL进行反射测量，以确认所发现的特性 在蟾蜍中发生得更为普遍，并对预测进行检验， 膜主导RNFL反射率; 2)用秋水仙碱去微管，以测试 假设RNFL的反射率来自于光的散射， 微管; 3)利用偏振光拓宽了RNFL的定量描述 反射率，并评估膜的相对贡献， 微管的反射机制;和 4)定量研究蟾蜍、大鼠、 和人类的关系，以便将反射测量与解剖学联系起来。 反射实验将使用一种独特的装置进行， 成像显微反射计，在体外制剂，和形态 将在相同的组织上获得测量。 由有关的 反射计以形态学的方法研究了各种RNFL的反射机理。 此外，所获得的数据将扩大定量描述 RNFL反射率，并提供了坚实的知识基础， 开发青光眼的RNFL评估方法。

The diagnosis and management of glaucoma requires sensitive methods for detecting and measuring damage to retinal nerve fibers. Newly-developed quantitative methods for optically assessing the retinal nerve fiber layer (RNFL) promise to enhance sensitivity and objectivity, but more basic knowledge is needed to interpret and improve them. The long-term objectives of this research are to provide a comprehensive quantitative description of the optical properties of the RNFL, and to establish the anatomical basis for its reflectance. Experiments with toad retina showed that the RNFL reflectance arises from uniformly-distributed cylindrical structures. A new theoretical model based on the ultrastructure of nerve fiber bundles suggests that axonal membranes dominate the reflectance, but preliminary experiments suggest that a substantial fraction of the RNFL reflectance comes from microtubules. The model predicts that membrane and microtubule mechanisms should behave differently in polarized light. The specific aims of this project are to: 1) perform reflectometry of rat RNFL to confirm that properties discovered in toad occur more generally, and to test the prediction that axonal membranes dominate the RNFL reflectance; 2) use colchicine to depolymerize microtubules in order to test the hypothesis that the RNFL reflectance arises from light scattered by microtubules; 3) use polarized light to broaden the quantitative description of the RNFL reflectance and to assess the relative contributions of membranes and microtubules to the reflectance mechanisms; and 4) study quantitatively the ultrastructure of RNFL tissue from toad, rat, and human in order to relate reflectometry to anatomy. Reflectometric experiments will be performed with a unique apparatus, an imaging microreflectometer, on in vitro preparations, and morphological measurements will be obtained on the same tissue. By relating reflectometry to morphology for a variety of RNFL reflectance mechanism. Additionally the data obtained will broaden the quantitative description of the RNFL reflectance and provide a solid foundation of knowledge upon which to develop RNFL assessment methods for glaucoma.