Sudden blindness in the fourth month of pregnancy led to diagnosis of moyamoya disease.

We report a 31-year-old woman in her 4th month of pregnancy who presented with a sudden decrease in her right visual acuity. The right ocular fundus showed marked retinal edema and a cherry-red spot. A cranial computerized tomographic scan showed cerebral infarction. Cerebral angiography disclosed moyamoya disease. Ischemia of the ophthalmic artery due to constriction of the origin of the internal carotid artery and hypercoagulability due to pregnancy have presumably caused visual impairment in this patient.