Causes include physical injury from ocular trauma or surgery, inflammatory conditions such as iritis or uveitis, angle closure glaucoma leading to iris occlusion of the trabecular meshwork, or intraocular tumors causing physical distortion of the iris. Mechanical anisocoria is an acquired defect that results from damage to the iris or its supporting structures. Examples include aniridia, coloboma and ectopic pupil. However, many cases are persistent.Ĭongenital anomalies in the structure of the iris may contribute to abnormal pupillary sizes and shapes that present in childhood. Physiologic anisocoria may be intermittent and even self-resolving. Light and near responses is intact, and the degree of anisocoria is typically equal in light and dark. The exact cause is unknown, but it is thought to be due to transient asymmetric supranuclear inhibition of the Edinger-Westphal nucleus that controls the pupillary sphincter. It is a benign condition with a difference in pupil size of less than or equal to 1 mm. Physiologic (also known as simple or essential) anisocoria is the most common cause of unequal pupil sizes, affecting up to 20% of the population. An injury or lesion in either pathway may result in changes in pupil size. A deficit of parasympathetic innervationĬorrect Answers: Anisocoria may be do to any of these items.Įxplanation 3 : “Generally, anisocoria is caused by impaired dilation (a sympathetic response) or impaired constriction (a parasympathetic response) of pupils. Question: Which of the following may cause anisocoria?ģ.
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