Optic neuritis is swelling and inflammation of the optic nerve of the eye. The optic nerve carries light signals from the back of your eye to your brain so you can see. If the optic nerve is swollen, damaged, or infected, you won’t be able to see clearly. You can find more information below.
What is optic neuritis?
Optic neuritis is a condition that occurs when swelling (inflammation) damages the optic nerve (a bundle of nerve fibers that transmit visual information from your eye to your brain). Common symptoms include pain during eye movements and temporary loss of vision in one eye.
Symptoms of optic neuritis may be the first sign of multiple sclerosis ( MS disease ) or may appear later in the course of MS disease. MS is a disease that causes inflammation and damage to the optic nerve as well as the nerves in your brain.
Besides MS disease, optic neuritis can occur with other conditions, including infections or immune system diseases such as lupus disease . Rarely, another disease called neuromyelitis optica causes inflammation of the optic nerve and spinal cord.
Most people who experience a single attack recover spontaneously without treatment. Sometimes steroid drugs can accelerate vision recovery after optic neuritis.
What causes optic neuritis?
The exact cause of optic neuritis is unknown. It is believed to develop when the immune system mistakenly targets the substance lining the optic nerve, causing inflammation and damage to its myelin.
Normally, myelin helps electrical impulses travel quickly from the eye to the brain and is converted into visual information. Optic neuritis disrupts this process and affects vision.
The following autoimmune conditions are often associated with optic neuritis:
- Multiple sclerosis: Multiple sclerosis is a disease in which your autoimmune system attacks the myelin sheath that covers nerve fibers in your brain. In people with optic neuritis, the lifetime risk of developing multiple sclerosis after an attack is approximately 50%. If a magnetic resonance imaging scan shows lesions in your brain, your risk of developing multiple sclerosis after optic neuritis is even greater.
- Neuromyelitis optica: In this case, the inflammation affects the optic nerve and spinal cord. Neuromyelitis optica is similar to multiple sclerosis, but neuromyelitis optica does not damage nerves in the brain the way multiple sclerosis does. However, neuromyelitis optica is more severe than MS, often with reduced recovery after an attack compared to MS.
- Myelin oligodendrocyte glycoprotein (MOG) antibody disorder: This condition can cause inflammation in the optic nerve, spinal cord, or brain. Similar to MS disease and neuromyelitis optica, recurrent episodes of inflammation may occur.
When the symptoms of optic neuritis are more complex, other associated causes need to be considered, including:
- Infections: Bacterial infections such as Lyme disease and syphilis , or viruses such as measles, mumps, and herpes can cause optic neuritis.
- Other diseases: Diseases such as sarcoidosis, Behçet’s disease and lupus can cause recurrent optic neuritis.
- Drugs and toxins: Some drugs and toxins have been associated with the development of optic neuritis. For example, methanol used in drugs, dyes and solvents used to treat tuberculosis has been associated with optic neuritis.
Who is at risk?
Risk factors for developing optic neuritis include:
- Age: This condition most commonly affects adults between the ages of 20 and 40.
- Gender: Women are much more likely than men to develop this problem.
- Skin color: It is more common in people with fair skin.
- Genetic mutations: Some genetic mutations can increase your risk of developing optic neuritis or multiple sclerosis.
What are the symptoms of optic neuritis?
Optic neuritis usually affects one eye, and its symptoms can include:
- Pain: Most people with this problem have eye pain that worsens with eye movement. Sometimes the pain is felt as a dull ache behind the eye.
- Loss of vision in one eye: Most people have at least a temporary decrease in their vision, but the extent of the loss varies from person to person. Noticeable vision loss usually develops within hours or days and resolves within a few weeks to months. In some people, vision loss is permanent.
- Visual field loss: It can occur in any pattern, such as loss of side vision, loss of central vision, or loss of peripheral vision.
- Color vision loss: This condition often affects color perception. You may notice that colors appear more vibrant than usual.
- Flashing lights: Some people affected by this problem report seeing flashing lights with their eye movements.
When should you 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:
- if you develop new symptoms such as eye pain or changes in your vision
- If your symptoms worsen or do not improve with treatment
- If you have unusual symptoms that may indicate a neurological disorder, such as loss of vision in both eyes, double vision, and numbness or weakness in one or more limbs
How is optic neuritis diagnosed?
You’re likely to see an ophthalmologist for diagnosis, which is usually based on your medical history and an exam. The ophthalmologist will likely do 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 on your eye and examines the structures at the back of your eye. This eye test evaluates the optic disc, where the optic nerve enters the retina in your eye. The optic disc swells in about one-third of people with optic neuritis.
- Pupil examination: Your doctor may move a flashlight in front of your eyes to see how the pupils react when exposed to bright light. If you have optic neuritis, your pupil will not constrict when exposed to light as it would in healthy eyes.
Other tests for diagnosis may include:
- Magnetic resonance imaging: This scan uses a magnetic field and pulses of radio wave energy to take pictures of your body. During an imaging to check for optic neuritis, you may receive an injection of a contrast solution to make the optic nerve and other parts of your brain more visible on the images. A magnetic resonance imaging is important to determine if you have damaged areas (lesions) in your brain. These lesions indicate a high risk of developing multiple sclerosis. Also, other causes of vision loss, such as tumors, are ruled out in this imaging procedure.
- Blood tests: A blood test may be done to check for infections or specific antibodies. People with severe optic neuritis may have this test to determine if they will develop neuromyelitis optica.
- Optical coherence tomography: This test measures the thickness of the retinal nerve fiber layer of the eye, which is usually thinner than optic neuritis.
- Visual field test: This test measures the peripheral vision of each eye to determine if there is any vision loss. Optic neuritis can cause any visual field loss.
- Visual evoked response: During this test, you sit in front of a screen where an alternate checkerboard pattern is displayed. Wires with small patches are placed on your head to record your brain’s responses to what you see on the screen. These types of tests let your doctor know if the electrical signals to your brain are slower than normal due to optic nerve damage.
Your doctor may ask you to come for follow-up exams two to four weeks after you start confirming the diagnosis.
How is optic neuritis treated?
This vision problem usually resolves on its own. In some cases, steroid medications are used to reduce inflammation in the optic nerve. Possible side effects of steroid therapy include weight gain, mood changes, facial flushing, stomach upset and insomnia.
Steroid therapy is usually given intravenously. Intravenous steroid therapy accelerates vision recovery, but does not affect the degree of improvement.
If steroid therapy fails and severe vision loss persists, a treatment called plasma exchange therapy may help some people improve their vision. Studies have not yet confirmed that plasma exchange therapy is effective.
Preventing multiple sclerosis (MS disease)
If the diagnosis is confirmed and you have two or more brain lesions evident on magnetic resonance imaging scans, you may benefit from multiple sclerosis medications such as interferon beta-1a or interferon beta-1b, which can delay or help prevent MS. These injectable drugs are used for people at high risk of developing MS. Possible side effects include depression, injection site irritation and flu-like symptoms.
Remember, your doctor will decide which medicine to take and how.
Optic neuritis complications
Complications from optic neuritis can include:
- Optic nerve damage: Most people have permanent optic nerve damage after an episode of optic neuritis, but the damage may not cause lasting symptoms.
- Decreased visual efficiency: Most people regain normal or near-normal vision within a few months, but a partial loss of color discrimination may persist. For some people, vision loss may also persist.
- Side effects of treatment: Steroid drugs used in treatment suppress your immune system, which causes your body to become more susceptible to infections. Other side effects include mood changes and weight gain.