Anisocoria is a condition characterized by an unequal size of the eyes' pupils. Affecting up to 20% of the population, anisocoria is often entirely harmless, but can be a sign of more serious medical problems.
Physiological anisocoria: About 20% of population has a slight difference in pupil size which is known as physiological anisocoria. In this condition, the difference between pupils is usually less than 1 mm.[4]
Adie tonic pupil: Tonic pupil is usually an isolated benign entity, presenting in young women. It may be associated with loss of deep tendon reflex (Adie's syndrome). Tonic pupil is characterized by delayed dilation of iris especially after near stimulus, segmental iris constriction, and sensitivity of pupil to a weak solution of pilocarpine.
Oculomotor nerve palsy: Ischemia, intracranial aneurysm, demyelinating diseases (e.g., multiple sclerosis), head trauma, and brain tumors are the most common causes of oculomotor nerve palsy in adults. In ischemic lesions of the oculomotor nerve, pupillary function is usually spared whereas in compressive lesions the pupil is involved.
Causes of anisocoria range from benign (normal) to life-threatening conditions. Clinically, it is important to establish whether anisocoria is more apparent in dim or bright light to clarify if the larger or smaller pupil is the abnormal one.
Anisocoria which is worsened (greater asymmetry between the pupils) in the dark suggests that the small pupil (which should dilate in dark conditions) is the abnormal pupil. This suggests Horner's syndromeormechanical anisocoria. In Horner's syndrome, sympathetic nerve fibers have a defect, therefore the pupil of the involved eye will not dilate in darkness. If the smaller pupil dilates in response to instillation of apraclonidine eye drops, this suggests Horner's syndrome is present.[citation needed]
Anisocoria which is worsened in bright light suggests that the larger pupil (which should constrict in bright conditions) is the abnormal pupil. This may suggest Adie tonic pupil, pharmacologic dilation, oculomotor nerve palsy, or damaged iris.[citation needed]
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.[citation needed]
Anisocoria is usually a benign finding, unaccompanied by other symptoms (physiological anisocoria).[citation needed] Old face photographs of patients often help to diagnose and establish the type of 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).[citation needed]
Acute onset anisocoria should be considered a medical emergency. 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 other intracranial mass can enlarge to a size where the third cranial nerve (oculomotor nerve) is compressed, resulting in uninhibited dilatation of the pupil on the same side as the lesion.[8]
English singer David Bowie exhibited anisocoria, owing to a teenage injury.[9]
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,[10] 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.[11][12]
^Lam, BL; Thompson, HS; Corbett, JJ (Jul 15, 1987). "The prevalence of simple anisocoria". American Journal of Ophthalmology. 104 (1): 69–73. doi:10.1016/0002-9394(87)90296-0. PMID3605282.
^John P.Whitcher; Paul Riordan-Eva (2007-10-18). Vaughan & Asbury's general ophthalmology (17th ed.). McGraw-Hill Medical. p. 293. ISBN978-0071443142.
^London, Richard; Richrer Erringer, Ellen; Wyafr, Harry J. (March 1991). "Variation and Clinical Observation With Different Conditions of Illumination and Accommodation". Investigative Ophthalmology & Visual Science. 32 (3): 501–9.
^Anisocoria. Medscape Reference. Accessed April 15, 2012.
^. It is also seen in some people who consume diphenydramine (brand name "Benadryl") for an extended period of time, or if an astringent eye drop like Visine is used in one eye and not the other, often in concurrence with the presence of contact lenses.van der Donck, I.; Mulliez, E.; Blanckaert, J. (2004), "Angel's Trumpet (Brugmansia arborea) and mydriasis in a child - A case report", Bulletin de la Société Belge d'Ophtalmologie, 292: 53–56, ISSN0081-0746
