We report a case with a paraophthalmic aneurysm that was wrapped with muslin because it was unclippable. Six months after wrapping, the patient developed gradual vision loss involving the ipsilateral eye. Both CT and MR studies demonstrated a loculated fluid collection with marked surrounding enhancement in the region of the previous surgery. Craniotomy revealed an abscess centered in the region of the aneurysmal wrapping. Pathological diagnosis was consistent with a foreign-body reaction with acute and chronic inflammation. Postoperatively the patient showed improvement in vision. We describe the MR findings in this case of muslin-induced optic arachnoiditis ("gauzoma").