bright conditions) is the abnormal pupil. This may suggest Adie tonic pupil, pharmacologic dilation, oculomotor nerve palsy, or damaged iris. A relative afferent pupillary defect (RAPD) also known as a Marcus Gunn pupil does not cause anisocoria. Some of the causes of anisocoria are life-threatening, including Horner's syndrome (which may be due to carotid artery dissection) and oculomotor nerve palsy (due to a brain aneurysm, uncal herniation, or head trauma). If the examiner is unsure whether the abnormal pupil is the constricted or dilated one, and if a one-sided drooping of the eyelid is present then the abnormally sized pupil can be presumed to be the one on the side of the ptosis. This is because Horner's syndrome and oculomotor nerve lesions both cause ptosis. Anisocoria is usually a benign finding, unaccompanied by other symptoms (physiological anisocoria). Old face photographs of patients often help to diagnose and establish the type of anisocoria. It should be considered an emergency if a patient develops acute onset anisocoria. These cases may be due to brain mass lesions which cause oculomotor nerve palsy. Anisocoria in the presence of confusion, decreased mental status, severe headache, or other neurological symptoms can forewarn a neurosurgical emergency. This is because a hemorrhage, tumor or another intracranial mass can enlarge to a size where the third cranial nerve (CN III) is compressed, which results in uninhibited dilatation of the pupil on the same side as the lesion. Popular culture English singer David Bowie exhibited anisocoria, owing to a teenage injury. In the season 10 Big Bang Theory Comic-Con special, Steve Molaro told a story about how he first met actor Judd Hirsch and was taken aback by his dilated pupil. One of the other writers researched it and discovered that Judd Hirsch has anisocoria. American actress Melissa Benoist developed this condition in 2015. American artist Ze Frank has the condition. He was listed as second author on a paper published in The Journal of Neuroscience, which was featured briefly in episode 21 of the show named a show on May 25, 2012 called My Pupils, explaining that his study of neuroscience of vision was motivated by his harmless anisocoria condition. Etymology Anisocoria is composed of prefix, root and suffix: prefix: aniso- from the Greek language (meaning: unequal), which in turn comes from an: meaning not and iso: meaning equal the root word: cor, from the Greek word "korē" meaning: