Naphazoline as a confounder in the diagnosis of carotid artery dissection.

Diagnosing Horner Syndrome can be difficult in the setting of an incomplete triad. A 27-year-old man presented with unilateral eyelid droop and intermittent ipsilateral headaches, having already seen 7 physicians. Physical examination revealed unilateral ptosis but no pupillary miosis or facial anhidrosis. Inspection of his clinical photographs revealed elevation of the ipsilateral lower eyelid, suggesting sympathetic dysfunction. On further questioning, he admitted to naphazoline dependence. Reexamination after ceasing the naphazoline unveiled the anisocoria. Vascular imaging subsequently revealed carotid dissection, and the patient was started on anticoagulant and antiplatelet therapy. The ptosis persisted after conjunctival Müllerectomy. External levator resection was recommended, but patient declined. This case underscores the importance of clinical photography, meticulous medical record review, and complete medication history including over-the-counter preparations. Clinicians should meticulously inspect the lower eyelid in cases of atypical blepharoptosis and consider the effects of eye drops when inspecting pupils for miosis.