This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Horner’s syndrome is a rare condition characterized by miosis (constriction of the pupil), ptosis (drooping of the upper eyelid), and anhidrosis (absence of sweating of the face). It is caused by damage to the sympathetic nerves of the face. The underlying causes of Horner’s syndrome vary greatly and may include a tumor, stroke, injury, or underlying disease affecting the areas surrounding the sympathetic nerves. In rare cases, Horner’s syndrome is congenital (present from birth) and may be associated with a lack of pigmentation of the iris (colored part of the eye). Treatment of Horner’s syndrome depends on the underlying cause.
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