Acute monocular visual loss secondary to anterior communicating artery aneurysm in a patient with sickle cell disease.

A patient with sickle cell disease had acute monocular visual loss with no visible vitreal or retinal abnormalities. A large aneurysm of the anterior communicating cerebral artery was found, with direct compression of the optic nerve. This represents a very rare presentation of a relatively common lesion. Consideration should always be given to compressive lesions as the cause of acute monocular visual loss in the absence of visible vitreal, retinal, or optic nerve disease.