LAUSR

BACKGROUND Optic perineuritis (OPN) is a rare orbital inflammatory disorder that primarily involves the optic nerve sheath (ONS). This study aimed to describe the clinical features of idiopathic OPN as well as OPN secondary to other infectious and inflammatory conditions in a Canadian case series as current literature on secondary OPN in Western countries is mostly limited to case reports. METHODS Retrospective case series of all patients seen in a tertiary neuro-ophthalmology practice with a diagnosis of OPN from 2014 to 2020. RESULTS A total of 21 patients (14 women, mean age 55.8) corresponding to 29 eyes with OPN were identified. Fifteen cases were associated with inflammatory or infectious conditions and only 6 were idiopathic. All idiopathic cases were unilateral. The most common secondary causes of OPN were anti-myelin oligodendrocyte glycoprotein (MOG) antibody disease (n = 4), syphilis (n = 3), sarcoidosis (n = 3), and giant cell arteritis (n = 3). At initial presentation, best-corrected visual acuity (BCVA) was 20/20 or better in 24% (n = 7) and visual field mean deviation (VF MD) was better than -5 dB in 34% of eyes (10/29). Treatment consisted of intravenous penicillin for syphilitic OPN and high-dose corticosteroids followed by oral taper with or without immunosuppressive therapy for non-syphilitic OPN. BCVA improved in 34% (10/29) and VF MD improved in 45% (13/29) eyes. CONCLUSION OPN primarily occurred in association with systemic inflammatory conditions, especially in bilateral cases. Syphilis must be ruled out in all patients. Anti-MOG antibody disease is an important, newly recognized secondary cause of OPN, and serologic testing should be included in the investigation of all patients with OPN.