The nature of fundal reflection has been investigated and discussed in a number of papers, and plays a crucial role in all double-pass imaging experiments such as the Campbell-Gubisch experiment. The retina behaves as a diffuse reflector, although it preserves a major part of the polarization of incoming light (acting as a metalized projection screen).
The location of the reflecting interface within the retina is a controversial issue, and involves more than a single contribution to the overall reflected light distribution.
Several authors have reported evidence of directionality in foveal reflection, which peaks toward the center of the pupil. The angular spread of the diffusion pattern is commonly interpreted as being due to the guiding effect of the photoreceptor outer segments, particularly in the bleached state, while directionality derives from the angular orientation of the cones. According to van Blockland, radial distribution of the reflection is approximately equal to the Stiles-Crawford effect.
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