Optic neuritis

Overview

Optic neuritis is an inflammation that damages the optic nerve, a bundle of nerve fibers that transmits visual information from your eye to your brain. Pain and temporary vision loss in one eye are common symptoms of optic neuritis. Optic neuritis is linked to multiple sclerosis, a disease that causes inflammation and damage to nerves in your brain and spinal cord. In some people, signs and symptoms of optic neuritis may be the first indication of multiple sclerosis. Most people who have a single episode of optic neuritis eventually recover their vision.

A close-up view of a human eye, showing the optic nerve and surrounding structures.

Causes

Optic neuritis occurs when the optic nerve becomes inflamed due to an immune system reaction that may be triggered by a viral infection. The immune system mistakenly targets the substance covering your optic nerve (myelin), resulting in inflammation and damage to the myelin. When the myelin is damaged, the transmission of visual information from your eye to your brain is disrupted.

The cause of optic neuritis is often unknown. However, optic neuritis is often associated with multiple sclerosis, which is a chronic disease that occurs when your immune system mistakenly attacks the myelin in your brain and spinal cord. Optic neuritis can also occur with other infections or immune diseases, such as Lyme disease or sarcoidosis.

Symptoms

The signs and symptoms of optic neuritis can be different in each person, but usually include:

- Blurry vision: This is often the first symptom of optic neuritis. You might notice that your vision is blurry in one or both eyes.

- Pain: Most people with optic neuritis experience pain when moving the eye. This pain usually precedes the loss of vision by a few days.

- Loss of color vision: You might notice that colors appear less vibrant than usual.

- Flashing lights: Some people see flashing or flickering lights.

- Loss of side (peripheral) vision.

Diagnosis

Your doctor will review your medical history and symptoms, and conduct a physical examination. He or she may perform several tests to diagnose optic neuritis and determine any underlying causes. These tests may include:

- Eye exam: Your doctor will examine your eyes to check for abnormal pupil reactions and other indications of optic neuritis.

- Visual evoked response test: This test measures how quickly your brain responds to visual stimuli.

- Magnetic resonance imaging (MRI): An MRI can provide detailed images of your brain and optic nerves, and can help identify inflammation or other abnormalities that may indicate optic neuritis.

Treatment

Treatment for optic neuritis depends on the cause. If a specific cause is identified, such as an infection, appropriate treatment will be started. If no cause is found, your doctor may recommend observation, as optic neuritis often improves on its own.

In some cases, steroid medications are used to reduce inflammation in the optic nerve. Steroids may speed up the recovery of vision, but they do not affect the final outcome of visual recovery.

If optic neuritis is associated with multiple sclerosis or another autoimmune condition, treatment of that condition may be needed to prevent further episodes of optic neuritis.

Prognosis

Most people recover good vision within 12 months of an episode of optic neuritis. However, the visual outcomes can vary greatly from person to person. Some people may have a near-complete recovery, while others may have persistent visual loss.