Has anyone information on the effects the pupil response has on the electroretinogram? Consider the consensual pupil constriction response: as this response is elicited by efferent input from the brain following stimulation of the other eye, there has to be efferent neural input arriving in the retina following a flash of light. I was wondering if this efferent input affects the ERG response? In addition, the constriction of the pupil occurs through smooth-muscle contraction, which might superimpose an EMG response onto the ERG I presume? I would appreciate any thoughts!