Benign unilateral episodic mydriasis, is a related entity in which intermittent episodes of pupillary asymmetrymydriasis occur in young adults, usually women. Each episode is self-limited, and the situation has not been associatedwith any systemic or neurologic disease. Usually related to migraine, some authors classify it as a limited form ofophthalmoplegic migraine. Selective serotonin reuptake inhibitors are effective in the treatment of depression,generalized anxiety disorder and a recurrently regarded as the pharmacotheraphy of choice. Probabl central inhibitoryeffects of SSRI extend to dilation-correlated neurons that inhibit the E.W. nucleus, the administration of SSRI would alsosuppress BUEM. The underlying physiopathology is not clear and may involve either parasympathetic deficiency orsympathetic hyperactivity affecting the iris. We consider that intermittent inhibition of dilation-corelated neurons in theEdinger West pal nucleus are responsible for the pupillary dilatations seen in BUEM.