[Mammalian pupil constriction to light in the presence of atropine in hamster. Part I. Hamster and visual rays].

Mammalian pupils constrict in reaction to lights. Miosis occurs via afferent and efferent nerves. Therefore, once the pupil is pretreated with atropine, miosis no longer occurs, even when the retina is intact. We found that hamster pupil constricts in reaction to light in the presence of atropine. We examined the relationship with pupillary size, light intensity, wavelength and intervals of darkness. Pupillary constriction was found when the retina was withdrawn, and the miosis was not affected by autonomic blocking agents, capsaicin pretreatment and tetrodotoxin, a nerve blocking agent. Hamster pupil reacts to lights (visible rays-ultraviolet) in the presence of atropine and in the absence of retinal function.