Background Optic perineuritis (OPN) is a rare orbital inflammatory disease which targets the optic nerve sheath. Although OPN is predominantly idiopathic, it can be secondary to an array of inflammatory, infective or malignant conditions, including giant cell arteritis (GCA).

Methods/Results We describe a case of a 75-year-old man with a four-week history of headaches with associated periorbital swelling, and monocular decrease visual acuity without significant constitutional or systemic symptoms. This was in the context of initially normal ESR and CRP. MRI head demonstrated bilateral OPN and GCA was subsequently confirmed based on temporal artery biopsy. He was managed with high dose prednisolone and upadacitinib.

Conclusions This case highlights the perineuritis as a rare manifestation of GCA.