Shot in the dark.

A 43-year-old woman presented with decreased vision in the right eye associated with painful eye movements 10 days after receiving her first dose of Pfizer-BioNTech coronavirus disease 2019 (COVID-19) vaccine (Pfizer Inc, New York, NY). Two days later she developed painful loss of vision in the left eye. Clinical presentation and magnetic resonance imaging findings were consistent with bilateral optic perineuritis transitioning to optic neuritis. Extensive evaluation including aquaporin-4 immunoglobin G (IgG), myelin oligodendrocyte glycoprotein IgG, and lumbar puncture was unrevealing. Visual acuity at nadir was counting fingers in both eyes, but after receiving intravenous steroids and plasma exchange vision eventually improved to 20/20 in each eye, although she was left with inferior visual field defects and bilateral optic disc pallor. This case highlights the diagnostic challenge in the evaluation of atypical optic neuritis with a review of post-COVID-19 vaccination-associated optic neuritis.