Chiasmal cavernous malformation. A rare cause of acute visual loss.

A rare cause of acute visual loss due to a chiasmal cavernous malformation is presented. Acute visual loss was due to local hemorrhage and volume expansion of the cavernous malformation inside and outside of the optic chiasma. This unique location of cavernous malformation is associated with a risk of permanent loss of the vision. Cavernous malformations of optic chiasma should be carefully evaluated and considered for possible preventative surgical resection before it becomes symptomatic.