In the last 15 years, researchers have discovered two new biomarkers of optic neuritis (distinct from multiple sclerosis): the immunoglobulins AQP4-IgG and MOG-IgG. A new study takes a fresh look at the incidence of the condition in light of the better understanding of these atypical etiologies.

The retrospective, population-based cohort included all residents of Olmsted County, Minnesota, diagnosed with optic neuritis between 2000 and 2018.

The researchers found an annual incidence of 3.9 per 100,000 people. Of the 110 patients with optic neuritis, 57% had a final diagnosis of multiple sclerosis, 29% had idiopathic disease, 5% had a MOG-IgG–associated disorder, 3% were diagnosed with AQP4-IgG seropositive neuromyelitis optic spectrum disorder (NMOSD), 2% had infectious disease, 2% had sarcoidosis and 1% each had seronegative NMOSD and medication-related neuritis.

The three patients positive for AQP4-IgG had more than one optic neuritis attack, and two had residual no-light-perception vision in at least one eye. Among the six MOG-IgG-positive patients, four had recurrent optic neuritis and all had a final visual acuity of 20/30 or better.

The researchers concluded that AQP4-IgG and MOG-IgG account for 9% of optic neuritis and both are associated with recurrent attacks; however, MOG-IgG optic neuritis has a better visual outcome than AQP4-IgG-associated neuritis.