Optochiasmal arachnoiditis has been reported following treatment of ruptured intracranial aneurysms, particularly arising from the anterior communicating artery. It has been suggested that the accompanying loss of vision is due to a muslin-induced optic neuropathy. This paper considers five cases of this condition; the response to steroid therapy was beneficial in three cases. A review of the literature is included. The arachnoiditis is considered to be due to an inflammatory response to muslin gauze placed close to the optic nerves and chiasm.