Optic neuritis occurs when swelling (inflammation) damages the optic nerve — a bundle of nerve fibers that transmits visual information from your eye to your brain. Common symptoms of optic neuritis include pain with eye movement and temporary vision loss in one eye. Signs and symptoms of optic neuritis can be the first indication of multiple sclerosis (MS), or they can occur later in the course of MS. MS is a disease that causes inflammation and damage to nerves in your brain as well as the optic nerve. Besides MS, optic nerve inflammation can occur with other conditions, including infections or immune diseases, such as lupus. Rarely, another disease called neuromyelitis optica causes inflammation of the optic nerve and spinal cord. Most people who have a single episode of optic neuritis eventually recover their vision without treatment. Sometimes steroid medications may speed the recovery of vision after optic neuritis. The exact cause of optic neuritis is unknown. It's believed to develop when the immune system mistakenly targets the substance covering your optic nerve, resulting in inflammation and damage to the myelin. Normally, the myelin helps electrical impulses travel quickly from the eye to the brain, where they're converted into visual information. Optic neuritis disrupts this process, affecting vision.