![]() In an eye without polycoria, the sphincter muscle is a part of the iris that functions to constrict and dilate the pupil. In cases of true polycoria there is an intact sphincter muscle, which contracts and dilates the pupils. To be considered true polycoria the extra pupil and the principal pupil must dilate and contract simultaneously with triggers such as light and administered drugs. In cases of true polycoria, there is an extra pupil that tends to be reactive to light and medication. There are no known or proposed trends in the occurrences of polycoria based on geographical location, age, gender, or season. The two kinds of polycoria are true polycoria and false pseudopolycoria. The prevalence of true polycoria is minimal. There have been cases diagnosed from age 3 to adulthood. These include (although not often) polar cataracts, glaucoma, abnormally long eyelashes, abnormal eye development, and poor vision. The general cause of polycoria is unknown, but there are some other eye conditions that are in association with polycoria. Polycoria is often congenital, however not diagnosed until adulthood. Polycoria is extremely rare, and other conditions are frequently mistaken for it. In the early history of China, double pupils were seen as a sign that a child would become a great king or sage. It results in decreased function of the iris and pupil, affecting the physical eye and visualization. It may be congenital or result from a disease affecting the iris. For additional information visit Linking to and Using Content from MedlinePlus.Polycoria is a pathological condition of the eye characterized by more than one pupillary opening in the iris. Any duplication or distribution of the information contained herein is strictly prohibited without authorization. Links to other sites are provided for information only - they do not constitute endorsements of those other sites. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. This site complies with the HONcode standard for trustworthy health information: verify here. Learn more about A.D.A.M.'s editorial policy editorial process and privacy policy. is among the first to achieve this important distinction for online health information and services. follows rigorous standards of quality and accountability. is accredited by URAC, for Health Content Provider (URAC's accreditation program is an independent audit to verify that A.D.A.M. Prior eye trauma, including surgery for cataractsĪ.D.A.M., Inc.Injury to the carotid or vertebral artery.Tumor, mass, or lymph node in the upper chest or lymph node causing pressure on a nerve may cause decreased sweating, a small pupil, or drooping eyelid all on the affected side (Horner syndrome).Seizure (pupil size difference may remain long after seizure is over).Infection of membranes around the brain ( meningitis or encephalitis).Increased intracranial pressure, because of brain swelling, intracranial hemorrhage, acute stroke, or intracranial tumor.Excess pressure in one eye caused by glaucoma. ![]() Brain tumor or abscess (such as pontine lesions).Bleeding inside the skull caused by head injury.Other causes of unequal pupil sizes may include: ![]() Other medicines that get in the eyes, including medicine from asthma inhalers, can change pupil size. The use of eye drops is a common cause of a harmless change in pupil size. ![]()
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