Directionality and alignment of the foveal receptors, assessed with light scattered from the human fundus in vivo.

The directionality of the foveal receptors of four subjects is assessed with a technique based on light scattering, and a psychophysical technique. The width and orientation of the absorbance diagram (difference between the scattering diagram in a bleached and unbleached state of the visual pigment) are compared with the Stiles-Crawford function. Results show that the directionality in the scattering diagram points into approximately the same direction as the S-C function, but the width of the scattering diagram is slightly less. The alignment of foveal receptors is studied by partially bleaching the retina with oblique incidence from a nasal and temporal direction. Comparison of the absorbance diagrams with a diagram obtained with normal incident bleaching shows no significant shift in their orientations.