The pupil.

PURPOSE OF REVIEW: To give an overview on topics of pupillary function selected according to their relevance in clinical neurology. Mainly publications of the last 3 years have been considered.

RECENT FINDINGS: The discovery of photosensitive retinal ganglion cells not serving vision, but serving circadian rhythm and the pupil initiated many studies. There is evidence that pupil reaction to light might be preserved even if all rods and cones are lost. Spontaneous pupillary contractions in darkness occur in sleepy subjects and have been used to quantify the state of alertness. Apraclonidine eye drops have been suggested to diagnose Horner syndrome. Iatrogenic cause and carotid artery dissection are the most frequently reported underlying causes of Horner syndrome. Anti-Hu antibodies may be associated with tonic pupils.

SUMMARY: Pupil studies in blind patients may give new insights into the function of the pupillary system. Testing for sleepiness by means of pupillography might be used more frequently. Testing for Horner syndrome still needs to be done with cocaine eye drops. Clinical evaluation has to be focused on detecting additional signs and symptoms. Unknown malignancy is very rare. In the tonic pupil (Adie syndrome) autoantibodies may play a role, in exceptional cases it might represent a paraneoplastic disorder.