I am wondering whether,  in  patients with severe retinal dystraphies, nystagmus (repetitive, jerky  eye movements) function similar to stimming in autism. Since the brain deams the visual information perceived by the remaining photoreceptors to be useless, nystagmus develops as a way to drown out this abberrent  information. Because nystagmus is repetitive, and disrupts fixation, the information obtained by the eyes can be tuned out. The movement of the eyes is also  atenuated.