Horner’s syndrome

Horner syndrome is a medical condition characterized by a specific set of symptoms affecting one side of the face. These symptoms include a slight drooping of the upper eyelid (ptosis), a constricted pupil (miosis), and decreased sweat production on the affected side of the face.1

This syndrome arises from an interruption of the sympathetic nerve pathway that runs from the brain to the face and eye. This interruption can be caused by various factors, including lesions, diabetes, vascular disease, head injury, or infections. While ptosis is a key feature, it is typically less severe than in other causes of eyelid drooping.21