Abnormal pupil condition: Argyll Robertson pupil

What it is

Argyll Robertson pupils (AR pupils) are bilateral small pupils that constrict when the subject focuses on a near object during accommodation, but do not constrict when exposed to bright light. AR pupils are often associated with the presence of syphilis and are extremely uncommon in developed countries.

History

The AR pupil was named after Douglas Moray Cooper Lamb Argyll Robertson, a Scottish ophthalmologist, who noted the association of the pupil condition with syphilis in 1869. Patients with AR pupils usually tested positive for syphilis. The AR pupil then became known as a reliable clinical sign of syphilis. They were formerly known as "Prostitute's pupils" because of their association with tertiary syphilis and because of the convenient mnemonic that, like prostitutes, they "accommodate but do not react".

The AR pupils are a highly specific sign of neurosyphilis. In general, pupils that accommodate during near vision but do not react under light exposure are said to show light-near dissociation. (link?)
(need to include that having AR pupils doesn't mean one HAS syphilis)

Clinical presentation

Typical Argyll Robertson pupils are small and irregular and react to accommodation, but not to light.

Initially, the pupil's response to light may only be sluggish and the accommodation reflex is much more pronounced but eventually, the light reflex disappears.

The exact site of the lesion is often debated but generally believed to be in the rostral mid-brain, proximal to the oculomotor nuclei. In some patients, magnetic resonance imaging studies have localized the lesion to the Edinger-Westphal nuclei.

The AR pupil has become a rare diagnostic sign of neurosyphilis. If neurosyphilis is suspected, examinations may reveal clues such as

• ptosis
• ataxia (using the positive Romberg's test)
• tremors of the mouth/tongue
• outstretched hands/whole body
• diminished/absent tendon reflexes
• impaired vibratory and joint position sense

The AR pupil may also indicate the presence of Sarcoidosis, multiple sclerosis and ocasionally, diabetes mellitus.