Argyll Robertson pupil

Argyll Robertson pupils (“AR pupils" or colloquially "prostitute's pupils") are bilateral small pupils that reduce in size on a near object (they “accommodate”), but do not constrict when exposed to bright light (they do not “react” to light). They are a highly specific sign of neurosyphilis, and might also be a sign of diabetic neuropathy. In general, pupils that “accommodate but do not react” are said to show light-near dissociation- i.e., it is the absence of a miotic reaction to light, both direct and consensual, with the preservation of a miotic reaction to near stimulus (accommodation-convergence). A video of AR pupils and light-near dissociation is available here.