Optic perineuritis is an uncommon variety of orbital inflammatory disease. A case with a 45-day history of headache and vomiting who was diagnosed with fibrillary astrocytoma of the right frontal lobe is reported. Progressive bilateral visual loss developing postoperatively was considered as bilateral optic perineuritis based on the pathological and radiological findings. However, extensive medical and surgical therapy failed to recover visual loss. By this case, the mechanisms and difficulties in the diagnosis were discussed.