Argyll-Robertson pupil

• Pupils small, irregular, and unequal; they do not dilate] properly in response to mydriatic drugs and fail to react to light, although they do constrict on accommodation
• Seen almost exclusively in neurosyphilis
  • NOTE: neurosyphilis is a tertiary manifestation of syphilis; tertiary syphilis more commonly involves the cardiovascular system; tertiary neurosyphilis may also cause meningitis with lymphocytic and plasmacytic infiltration; causes CSF pleocytosis with low glucose; infective agent is a spirochete
• Exact location of lesion is uncertain but is believed to be in the tectum of the midbrain proximal to the oculomotor nuclei where the descending pupillodilator fibers are in close proximity to the light reflex fibers
• Neurosyphilis is also associated with concentric constriction (visual field constriction no matter how far away the object being viewed is) of the visual field
• Distinguishable from Gunn’s pupillary sign
  • slowness of response to light along with failure to sustain pupillary constriction