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 (MS), a disease that causes inflammation and damage to nerves in your brain and spinal cord. Signs and symptoms of optic neuritis can be the first indication of multiple sclerosis, or they can occur later in the course of MS. Besides MS, optic neuritis can occur with other infections or immune diseases, such as lupus.

Most people who have a single episode of optic neuritis eventually recover their vision. Treatment with steroid medications may speed up vision recovery after optic neuritis.

Source: http://www.mayoclinic.com

Symptoms

Optic neuritis usually affects one eye. Symptoms might include:

• Pain. Most people who develop optic neuritis have eye pain that's worsened by eye movement. Sometimes the pain feels like a dull ache behind the eye.
• Vision loss in one eye. Most people have at least some temporary reduction in vision, but the extent of loss varies. Noticeable vision loss usually develops over hours or days and improves over several weeks to months. Vision loss is permanent in some cases.
• Visual field loss. Side vision loss can occur in any pattern.
• Loss of color vision. Optic neuritis often affects color perception. You might notice that colors appear less vivid than normal.
• Flashing lights. Some people with optic neuritis report seeing flashing or flickering lights with eye movements.

When to see a doctor

Eye conditions can be serious. Some can lead to permanent vision loss, and some are associated with other serious medical problems. Contact your doctor if:

• You develop new symptoms, such as eye pain or a change in your vision.
• Your symptoms worsen or don't improve with treatment.
• You have unusual symptoms, including numbness or weakness in one or more limbs, which can indicate a neurological disorder.

Source: http://www.mayoclinic.com

Causes

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 (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 optic neuritis increases further if an MRI scan shows lesions on your brain.

• Neuromyelitis optica. In this condition, inflammation recurs 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.

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.
• Other diseases. Diseases such as sarcoidosis and lupus can cause recurrent optic neuritis.
• Drugs. Some drugs have been associated with the development of optic neuritis. They include quinine and some antibiotics.

Source: http://www.mayoclinic.com

Diagnosis

You're likely to see an ophthalmologist for a diagnosis, which is generally based on your medical history and an exam. The ophthalmologist likely will perform the following eye tests:

• A routine eye exam. Your eye doctor will check your vision and your ability to perceive colors and measure your side (peripheral) vision.
• Ophthalmoscopy. During this examination, your doctor shines a bright light into your eye and examines the structures at the back of your eye. This eye test evaluates the optic disk, where the optic nerve enters the retina in your eye. The optic disk becomes swollen in about one-third of people with optic neuritis.
• Pupillary light reaction test. Your doctor may move a flashlight in front of your eyes to see how your pupils respond when they're exposed to bright light. Pupils in eyes affected by optic neuritis don't constrict as much as those in healthy eyes do when stimulated by light.

Other tests to diagnose optic neuritis might include:

• Magnetic resonance imaging (MRI) scan. An MRI scan uses a magnetic field and pulses of radio wave energy to make pictures of your body. During an MRI to check for optic neuritis, you might receive an injection of a contrast solution to make the optic nerve and other parts of your brain more visible on the images.

  An MRI is important to determine whether there are damaged areas (lesions) in your brain. Such lesions indicate a high risk of developing multiple sclerosis. An MRI can also rule out other causes of visual loss, such as a tumor.

• Blood tests. A blood test is available to check for antibodies for neuromyelitis optica. People with severe optic neuritis may undergo this test to determine whether they're likely to develop neuromyelitis optica.
• Optical coherence tomography (OCT). This measures the thickness of the retinal nerve fiber layer, which is often thinner from optic neuritis.
• Visual evoked response. During this test, you sit before a screen on which an alternating checkerboard pattern is displayed. Attached to your head are wires with small patches to record your brain's responses to the visual stimuli. This type of test detects the slowing of electrical conduction resulting from damage to the optic nerve.

Your doctor is likely to ask you to return for follow-up exams two to four weeks after your symptoms begin to confirm the diagnosis of optic neuritis.

Source: http://www.mayoclinic.com

Complications

Complications arising from optic neuritis may include:

• Optic nerve damage. Most people have some permanent optic nerve damage after an episode of optic neuritis, but the damage might not cause symptoms.
• Decreased visual acuity. Most people regain normal or near normal vision within several months, but a partial loss of color discrimination might persist. For some people, vision loss persists after the optic neuritis has improved.
• Side effects of treatment. Steroid medications used to treat optic neuritis subdue your immune system, which causes your body to become more susceptible to infections. Other side effects include mood changes and weight gain.

Risk factors

Risk factors for developing optic neuritis include:

• Age. Optic neuritis most often affects adults ages 20 to 40.
• Sex. Women are much more likely to develop optic neuritis than men are.
• Race. In the United States, optic neuritis occurs more frequently in whites than it does in blacks.
• Genetic mutations. Certain genetic mutations might increase your risk of developing optic neuritis or multiple sclerosis.

Source: http://www.mayoclinic.com