- sedative-hypnotics ie. opiates, barbituates, PCP
- alpha-2 agonists ie. clonidine
- pontine lesions caused by bilateral disruption of the descending sympathetic pathways
- other sympathetic lesions ie causes of Horners syndrome
- Argyll Robertson pupil associated with neurosyphilis where pupils are small and irregular and constrict much less to light than to accommodation (light-near dissociation)
Source
Blumenfeld, Hal MD Ph D. Neuroanatomy through Clinical Cases. 2002.
Ford: Clinical Toxicology, 1st ed.