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Optic Neuritis (cont.)

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What causes optic neuritis?

The precise cause of optic neuritis is unknown, but it is thought to be a type of autoimmune disorder. The immune system is generally used by the body to fight infection by creating a reaction that combats bacteria, viruses, fungi, and other foreign proteins. In autoimmune diseases, this reaction is mistakenly directed against a normal part of the body, creating inflammation and potential damage. In the case of optic neuritis, the optic nerve becomes swollen and its function is impaired. Inflammation and destruction of the protective myelin sheath that coats and insulates the optic nerve, plus direct damage to the nerve axons results in loss of vision, which may be temporary or permanent.

Optic neuritis is frequently an indication of multiple sclerosis (MS), a disease in which the immune system attacks the myelin sheath covering nerve fibers in the brain and spinal cord, resulting in inflammation and nerve damage. Optic neuritis typically resolves initially but often recurs.

In 15%-20% of people who eventually develop multiple sclerosis, optic neuritis is their first symptom. The risk of developing multiple sclerosis following one episode of optic neuritis is approximately 50% within 15 years of any first episode of optic neuritis. Various studies have shown that approximately 50% of patients who have optic neuritis for the first time will have MRI brain and/or spinal cord abnormalities consistent with MS at the time of the initial optic neuritis.

Neuromyelitis optica is another autoimmune condition in which demyelination occurs both in the spinal cord and both optic nerves but often sparing the brain. In this infrequent condition, the patient can experience weakness or paralysis in the limbs and/or bladder and bowel dysfunction, as well as loss of vision.

Approximately one-half of initial cases of optic neuritis are presumed to be an inflammatory reaction developing one week to one month following an upper-respiratory viral infection.

There are a variety of conditions that can affect the optic nerve, causing symptoms similar to optic neuritis. These include various optic neuropathies due to infection, trauma, hereditary conditions, toxic or nutritional problems, compressive lesions of the optic nerves, and vascular diseases, including arteritic optic neuropathy, diabetes, and glaucoma. Treatment of these optic neuropathies is directed at the underlying disease.

What are optic neuritis risk factors?

Optic neuritis risk factors include trauma, hereditary conditions, toxic or nutritional problems, compressive lesions of the optic nerves, and vascular diseases, including arteritic optic neuropathy, diabetes, and glaucoma.

Medically Reviewed by a Doctor on 8/22/2016

Source: MedicineNet.com
https://www.medicinenet.com/optic_neuritis/article.htm

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