Knighton R W, Huang X R
Bascom Palmer Eye Institute, University of Miami School of Medicine, Florida 33101, USA.
Invest Ophthalmol Vis Sci. 1999 Mar;40(3):639-47.
To measure and describe the reflectance properties of a mammalian retinal nerve fiber layer (RNFL) and to determine the mechanisms responsible for the RNFL reflectance.
An isolated rat retina suspended across a slit in a black membrane and mounted in a black perfusion chamber provided high quality images of the RNFL. Imaging microreflectometry was used to measure RNFL reflectance at wavelengths from 400 nm to 830 nm and as a function of illumination angle.
The directional reflectance of rat RNFL at all wavelengths was consistent with the theory of light scattering by cylinders; each nerve fiber bundle scattered light into a conical sheet coaxial with the bundle. There was no evidence of a noncylindrical component at any wavelength. Measured reflectance spectra were consistent between animals, similar to ones previously measured in macaque, and varied with scattering angle. All spectra could be described by a two-mechanism cylindrical scattering model with three free parameters.
At all wavelengths the reflectance of rat RNFL arises from light scattering by cylindrical structures. The highly directional nature of this reflectance can be an important source of measurement variability in clinical assessment of the RNFL. The reflectance spectra reveal a combination of mechanisms: At wavelengths shorter than approximately 570 nm the reflectance comes from cylinders with diameters much smaller than the wavelength, but at wavelengths longer than approximately 680 nm the reflectance comes from cylinders with effective diameters of 350 nm to 900 nm.
测量并描述哺乳动物视网膜神经纤维层（RNFL）的反射特性，并确定造成RNFL反射的机制。
将分离的大鼠视网膜横跨黑色膜上的狭缝悬挂，并安装在黑色灌注室中，以提供RNFL的高质量图像。成像显微反射测量法用于测量400纳米至830纳米波长范围内以及作为照明角度函数的RNFL反射率。
大鼠RNFL在所有波长下的定向反射率与圆柱体光散射理论一致；每个神经纤维束将光散射到与该束同轴的锥形片中。在任何波长下均未发现非圆柱形成分的证据。动物之间测得的反射光谱一致，类似于先前在猕猴中测得的光谱，并随散射角而变化。所有光谱都可以用具有三个自由参数的双机制圆柱散射模型来描述。
在所有波长下，大鼠RNFL的反射率均源于圆柱形结构的光散射。这种反射率的高度定向性质可能是RNFL临床评估中测量变异性的重要来源。反射光谱揭示了多种机制的组合：在波长小于约570纳米时，反射率来自直径远小于波长的圆柱体，但在波长大于约680纳米时，反射率来自有效直径为350纳米至900纳米的圆柱体。
