The optic nerve carries visual information from your eye to your brain. Optic neuritis (ON) is when your optic nerve becomes inflamed. ON can flare up suddenly from an infection or nerve disease.
The inflammation usually causes temporary vision loss that typically happens in only one eye. As you recover and the inflammation goes away, your vision will likely return.
Those with ON sometimes experience pain. There are other conditions with symptoms that resemble the symptoms of ON. Doctors may use optical coherence tomography (OCT) or magnetic resonance imaging (MRI) to help reach the correct diagnosis.