What is a common symptom of Horner's syndrome?

Horner's syndrome is characterized by a disruption of sympathetic nerve pathways to the eye and is commonly associated with a specific set of symptoms. One hallmark feature of this condition is pupil constriction, also known as miosis. This occurs due to the loss of sympathetic stimulation that typically dilates the pupil. In Horner's syndrome, the affected eye will have a smaller pupil compared to the unaffected eye, demonstrating pronounced constriction.

This condition can also present with additional signs, such as ptosis (drooping of the eyelid) and anhidrosis (lack of sweating) on the affected side of the face. Pupil constriction in Horner's syndrome is a distinctive finding that helps differentiate it from other conditions affecting the eye. Recognizing this symptom is crucial for diagnosing the underlying cause, which can range from benign to serious, such as a tumor or a neurological issue.