Optic Neuritis

Optic neuritis is swelling and inflammation of the optic nerve, the cable that carries visual signals from the back of the eye to the brain. It typically causes blurred or dim vision, faded colors, and pain that gets worse when you move the eye. It usually affects one eye and can come on over hours or days.

The American Academy of Ophthalmology lists autoimmune diseases such as multiple sclerosis and MOGAD, and viral infections such as mumps, measles, or the flu, as causes of optic neuritis. Optic neuritis is sometimes the first sign of multiple sclerosis. Treatment often includes corticosteroids, which can speed recovery, and many people regain much of their vision, although those with multiple sclerosis or other conditions may not fully recover.

In lawsuits, optic neuritis comes up mainly in drug injury claims. Some medicines, including certain immune-modulating drugs, list optic neuritis as a possible side effect. It is also important to distinguish it from a different optic nerve injury, non-arteritic anterior ischemic optic neuropathy (NAION), in which blood flow to the nerve is cut off and vision loss is usually painless. NAION is the injury alleged in lawsuits over semaglutide drugs like Ozempic and Wegovy. Because the two conditions have different causes, the exact diagnosis in your medical records matters a great deal for whether a claim fits a particular lawsuit.

If you had sudden vision loss while taking a medication, ask your eye doctor what the diagnosis was and whether other causes were ruled out. See the Ozempic lawsuit page and our guide on multidistrict litigation.