Choi Stacey S, Doble Nathan, Lin Julianna, Christou Julian, Williams David R
Center for Visual Science, University of Rochester, Rochester, New York 14627, USA.
J Opt Soc Am A Opt Image Sci Vis. 2005 Dec;22(12):2598-605. doi: 10.1364/josaa.22.002598.
In images of the human fundus, the fraction of the total returning light that comes from the choroidal layers behind the retina increases with wavelength [Appl. Opt. 28, 1061 (1989); Vision Res. 36, 2229 (1996)]. There is also evidence that light originating behind the receptors is not coupled into the receptor waveguides en route to the pupil [S. A. Burns et al., Noninvasive Assessment of the Visual System, Vol. 11 of 1997 Trends in Optics and Photonics Series, D. Yager, ed. (Optical Society of America, 1997), p. al; Invest. Ophthalmol. Visual Sci. 38, 1657 (1997)]. These observations imply that the contrast of images of the cone mosaic should be greatly reduced with increasing wavelength. This hypothesis was tested by imaging the light distributions in both the planes of the photoreceptors and the pupil at three wavelengths, 550, 650, and 750 nm, with the Rochester adaptive optics ophthalmoscope. Surprisingly, the contrast of the retinal images varied only slightly with wavelength. Furthermore, the ratio of the receptorally guided component to the total reflected light measured in the pupil plane was found to be similar at each wavelength, suggesting that, throughout this wavelength range, the scattered light from the deeper layers in the retina is guided through the receptors on its return path to the pupil.
在人眼底图像中，来自视网膜后方脉络膜层的总回射光的比例随波长增加而升高[《应用光学》28, 1061 (1989)；《视觉研究》36, 2229 (1996)]。也有证据表明，源自感受器后方的光在其射向瞳孔的途中未耦合到感受器波导中[S. A. 伯恩斯等人，《视觉系统的无创评估》，《光学与光子学趋势系列》第11卷，D. 亚格编(美国光学学会，1997)，第al页；《眼科研究与视觉科学》38, 1657 (1997)]。这些观察结果表明，随着波长增加，视锥细胞镶嵌图像的对比度应会大幅降低。利用罗切斯特自适应光学检眼镜在550、650和750纳米这三个波长下对光感受器平面和瞳孔平面中的光分布进行成像，对这一假设进行了检验。令人惊讶的是，视网膜图像的对比度随波长变化很小。此外，发现在瞳孔平面中测得的感受器引导成分与总反射光的比率在每个波长下都相似，这表明在整个该波长范围内，来自视网膜较深层的散射光在其返回瞳孔的路径上是通过感受器引导的。
