Department of Emergency Medicine

UMEM Educational Pearls

Category: Neurology

Title: Aniscoria - Unequal Pupils

Keywords: anisocoria, pupillary response, pupils (PubMed Search)

Posted: 8/27/2008 by Aisha Liferidge, MD (Updated: 4/26/2024)
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  • Anisocoria is when pupillary size is assymetric.
  • Anisocoria suggests a lesion in the efferent fibers supplying the pupillary sphinter muscles.
  • In order to localize the causative lesion, you must first determine which pupil is abnormal, the smaller one or the larger one.
  • The smaller pupil is abnormal when the degree of assymetry is more pronounced in darkened settings.
  • The larger pupil is abnormal when the degree of assymetry is more pronounced in bright light.

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