Optic nerve apoplexy. Report of two cases.

Two patients who suffered loss of vision due to spontaneous optic nerve hematomas are described. The hemorrhage was contained within the pial confines of the involved optic nerve, although there was some extension more posteriorly. The diagnosis of an intraneural cryptic arteriovenous malformation was histologically confirmed in one case and was supported by evidence in the other. Surgical evacuation by the subfrontal approach was undertaken and visual function improved.