The exact cause of optic neuritis is unknown. However, optic neuritis is believed to develop when the immune system mistakenly targets the substance covering your optic nerve (myelin), 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.

The following autoimmune conditions often are associated with optic neuritis:

  • Multiple sclerosis. Multiple sclerosis is a disease in which your autoimmune system attacks the myelin sheath covering nerve fibers in your brain and spinal cord. In people with optic neuritis, the risk of developing multiple sclerosis following one episode of optic neuritis is about 50 percent over a lifetime.

    Your risk of developing multiple sclerosis after optical neuritis increases further if an MRI scan shows lesions on your brain.

  • Neuromyelitis optica. In this condition, inflammation occurs in the optic nerve and spinal cord. Neuromyelitis optica has similarities to multiple sclerosis, but neuromyelitis optica doesn't cause damage to the nerves in the brain as often as multiple sclerosis does. Optic neuritis arising from neuromyelitis optica tends to be more severe than optic neuritis associated with multiple sclerosis.

Other autoimmune conditions, such as sarcoidosis and systemic lupus erythematosus, have also been associated with optic neuritis.

Other factors that have been linked to the development of optic neuritis include:

  • Infections. Bacterial infections, including Lyme disease, cat-scratch fever and syphilis, or viruses such as measles, mumps and herpes can cause optic neuritis.
  • Drugs. Some drugs have been associated with the development of optic neuritis. One of these drugs is ethambutol (Myambutol), which is used to treat tuberculosis.
Feb. 18, 2014

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