Long-Term Outcome and Prognosis of Idiopathic Optic Neuritis: A Cohort Study

Abstract

Introduction: Patients diagnosed with optic neuritis (ON) who did not fulfil the diagnostic criteria for multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMO-SD), tested negative myelin oligodendrocyte glycoprotein immunoglobulin G and for which a systemic disease has been excluded are classified as having idiopathic ON (IDON).

Methods: This was a monocentric retrospective observational study. Inclusion criteria were as follows: patients with IDON, absence of an alternative diagnosis during the first 2 years, follow-up of at least 5 years.

Results: Thirty-six patients were included. After a median follow-up of 9 years, a diagnosis of IDON was retained for 77.8% (n = 28) of patients, whereas 22.2% (n = 8) converted to an alternative diagnosis after a median of 6 years. Four patients converted to MS, two to clinically isolated syndrome and two to seronegative NMO-SD. Among the 28 patients who remained diagnosed with IDON, 42.9% (n = 12) experienced recurrent ON, occurring mostly (90%) within the first 5 years of the disease. Maintenance therapy was initiated in 10 of the 12 patients, among whom 6 patients had no recurrence under treatment. For the 28 patients who remained with IDON, the final best corrected visual acuity (BCVA) was variable. Respectively, 35.7% and 25.9% of patients had a BCVA inferior to 0.5 and 0.2, whereas 50% recovered a final BCVA of 10/10.

Conclusion: A significant proportion of the cohort converted to an alternative diagnosis after 2 years, encouraging an extended follow-up of IDON patients. Maintenance therapies were often effective in case of recurrent ON.

Keywords: idiopathic; multiple sclerosis; myelin oligodendrocyte glycoprotein; neuromyelitis optica; optic neuritis.

FIGURE 1

Optic neuritis recurrences in idiopathic optic neuritis patients and impact of treatment on disease course.