A young, otherwise healthy man presented with an acute retinal artery obstruction following excessive use of oxymethazolone hydrochloride 0.5% (Afrin) nasal spray. Platelet coagulation studies indicated a platelet aggregation hypersensitivity to adenosine diphosphate and epinephrine. A predisposition for sympathomimetic drug-induced platelet fibrin embolus formation appears to be the cause of the retinal artery obstruction in this case.