July 16, 2012 Miosis or constriction of the pupil is normal in infancy and old age. The physiological cause is a bright light, sleep, and accommodation (see synkinesis). The most common non-physiological causes for the miosis are a treatment with pilocarpine eye drops (glaucoma), drug intoxication, Horner’s syndrome, Argyll-Robertson pupils, coma, iridocyclitis, and some lesions of the pons.
Argyll-Robertson pupils are mutually narrow pupils that do not react to light but react when looking in the proximity. The cause is the injury of the pons, most neurolues.