Evidence for alteration in photoreceptor orientation.

The effect of incident light, its point of origin, and its magnitude on receptor orientation was determined. A non-invasive test of vision, the Stiles-Crawford Effect (SCE), was used to investigate retinal directional sensitivity and alignment. The simple act of monocular black patching for a period of three to five days caused marked reduction in directional sensitivity and/or apparent dispersal of alignments. Recovery occurred in a comparable time period in normal adults 20 to 50 years of age. Special painted iris contact lenses with displaced pupillary apertures were worn to investigate the factors influencing alignment. Both light induced effects which caused alignment to shift toward a displaced aperture, and mechanical factors resulting in other alignment shifts were recorded. Thus, retinal receptors and/or associated anatomic components are apparently phototropic and subject to multiple forces influencing their directionality and/or alignment, and the milieu of the retinal receptor is active.