Optic Neuritis

What is optic neuritis?

Optic neuritis (ON) is a type of neuropathy (nerve disease) that can cause eye pain and vision loss or vision changes. It happens when inflammation affects signals traveling through your optic nerve, which connects your eyes and brain.

The cells that make up your optic nerve have a fatty coating called a myelin sheath. When you have ON, that sheath deteriorates. The coating is protective. Without it, the nerve cells can’t send signals properly. That’s why various forms of vision loss are common symptoms of this condition.

Types of this condition

There are three main types of optic neuritis:

• Typical. This type usually affects one eye only, and most people recover within several days, even without treatment. (But experts still strongly recommend treatment for other reasons.)
• Atypical. This type usually affects both eyes, and people with it usually don’t recover quickly. Research links it with several other complex neurological (nervous system-related) disorders.
• Pediatric. This is the childhood form of optic neuritis. While similar to the other two types, there are also some important differences. This form usually has a better overall outlook.

How common is this condition?

Optic neuritis is common. In the U.S., there are about 5 new cases per 100,000 people each year.

What are the symptoms?

Optic neuritis symptoms all revolve around your eyes and disruptions in vision. The changes usually stem from “retrobulbar” (meaning “behind the eyeball”) effects of optic neuritis.

Symptoms can include:

• Eye pain. Over 90% of people with optic neuritis experience pain as a symptom, which usually worsens when you move your eyes. But in some cases, atypical optic neuritis may not cause pain at all.
• Vision acuity loss. This means your vision is less clear or sharp. This is usually more severe in pediatric optic neuropathy.
• Visual field defects or vision loss. These are gaps or other decreases in vision that only affect part of your visual field. With optic neuritis, the gap is usually in the center of your visual field.
• Color vision loss (dyschromatopsia). This is a decrease in how well you see colors, especially red.

What causes optic neuritis?

Optic neuritis happens when inflammation damages your optic nerve. There are several possible causes of that inflammation:

• Autoimmune and inflammatory conditions.
• Infections.
• Drugs and toxins.
• Other conditions.

Optic neuritis can also have an unknown cause (idiopathic).

Autoimmune and inflammatory conditions

Researchers suspect that autoimmune and inflammatory conditions are a major cause or contributing factor to optic neuritis. But they also suspect that the specific autoimmune conditions involved can vary depending on what type of optic neuritis you have.

• Typical optic neuritis. Multiple sclerosis (MS) is the main condition linked to typical optic neuritis. Research shows that optic neuritis is often the first “event” that signals a person has MS, and that approximately 50% of people with typical optic neuritis will develop MS within 15 years.
• Atypical optic neuritis. Research links atypical optic neuritis to neuromyelitis optica (NMO) and MOG-antibody-associated disease (MOGAD). Experts originally thought MS, NMO and MOGAD were the same condition until they discovered that NMO and MOGAD involve different specific antibodies.

Infections

Your nerves are vulnerable to damage (neuropathy) from infections, and your optic nerve is no exception. Infections are often a triggering event that causes pediatric optic neuritis.

Four main types of pathogens can cause infections:

Viral conditions are a common cause of optic neuritis, especially the pediatric form. Examples of these viruses include:

• Varicella (the virus that causes chickenpox and shingles).
• Herpes simplex virus types 1 and 2.
• Cytomegalovirus.
• HIV.
• Mosquito-carried viruses.
• Childhood viruses like measles.

Bacteria that cause optic neuritis usually pass to humans from animals or insects. Examples of bacteria or bacterial conditions include:

• Cat scratch fever.
• Lyme disease (from ticks).
• Tuberculosis.
• Syphilis.

Fungal conditions that can cause optic neuritis include:

• Cryptococcus neoformans (cryptococcosis).
• Various candida species (candidiasis).
• Histoplasma capsulatum (histoplasmosis).
• Multiple types of aspergillus (aspergillosis).

Parasitic conditions that can cause optic neuritis often spread to humans from pets, especially cats and dogs. Examples include:

• Toxoplasma gondii (toxoplasmosis) from cats.
• Toxcocara canis (toxocariasis) from dogs.

Drugs and toxins

Prescribed medications and nonprescribed drugs can sometimes cause optic neuropathy (nerve damage). The most common types of drugs and toxins that can do this include:

• Medications that treat infections, like ethambutol, chloramphenicol, isoniazid or sulfa-type antibiotics.
• Arrhythmia medications, like amiodarone or digoxin.
• Quinine-type malaria medications, including chloroquine and hydroxychloroquine.
• Anticancer medications, like methotrexate, vincristine and tamoxifen.
• Tobacco and nicotine products.
• Alcohol or methanol (sometimes known as “wood alcohol”).

Other causes

Several other conditions can also cause or contribute to optic neuropathy. They include:

• Lack of blood flow (ischemia). If your optic nerve isn’t getting enough blood flow, its cells can stop working correctly, leading to optic nerve damage.
• Vitamin deficiencies. Low B vitamin levels, especially vitamin B12, can cause permanent, severe nerve damage.
• Nerve compression. This is when something presses on your optic nerve(s), causing damage and inflammation. Tumors and conditions like hydrocephalus can cause it.
• Metabolic conditions like Type 2 diabetes. The risk of having optic nerve damage goes up as diabetes becomes more advanced. The risk is even greater when you have higher blood sugar levels.

What are the risk factors for optic neuritis?

Certain factors make you more likely to develop optic neuritis. They include:

• Sex. Women and people assigned female at birth (AFAB) are more likely to develop typical optic neuritis than men and people assigned male at birth (AMAB). Research indicates the AFAB-to-AMAB ratio is as low as 3-to-2 and as high as 5-to-1. The exception is atypical optic neuritis, which is more likely to affect people AMAB.
• Age. Typical optic neuritis is most likely to happen between ages 20 and 40. Atypical optic neuritis is more likely to happen before age 18 or after age 50. Pediatric optic neuritis usually happens before age 10.
• Race. People who are white are more likely to develop optic neuritis. Race also may play a role in whether or not a person develops MS after having optic neuritis. Research shows people of Asian descent are much less likely to develop MS after having optic neuritis.
• Location. Where you live can affect your risk of developing MS. People who live farther from Earth’s equator have a slightly higher risk of developing it. Experts suspect this has to do with sun exposure and/or vitamin D levels.
• Having another autoimmune disease. People with autoimmune conditions like lupus erythematosus, sarcoidosis and Behçet’s disease have a higher risk of developing optic neuritis.

What are the complications of optic neuritis?

Vision loss is the main complication of optic neuritis. Your eye care specialist can tell you about any other complications that are possible or likely with your case.

How is optic neuritis diagnosed?

An eye care specialist may suspect optic neuritis based on:

• Your symptoms.
• Your medical history.
• If you have (or could have) another condition that could cause optic neuritis.

An eye exam is a key part of the process. The exam will include the following:

• Visual acuity.
• Visual field.
• Ability to see color.
• Pupil reflexes.
• Slit lamp exam.

The following tests are also likely early on:

• Visual evoked potentials.
• Optical coherence tomography.

If the above checks and test results are consistent with optic neuritis, and another condition doesn’t better explain your symptoms, your eye care provider will probably refer you to a specialist. This may be a neurologist or a neuro-ophthalmologist (an eye care specialist who focuses on retinal and optic nerve issues and conditions).

Further testing

A magnetic resonance imaging (MRI) scan is a key part of diagnosing optic neuritis. The scan will involve contrast, a substance that makes tissue changes more visible on the scan. If you have optic neuritis, the affected optic nerve(s) will look brighter than a healthy optic nerve.

An MRI is important because it can detect brain lesions, which can be key indicators of MS. MRIs can also detect other lesions affecting your optic nerve and/or spinal cord, which are signs of NMO or MOGAD.

There are also several lab tests your provider might recommend. Lab testing is likely if:

• It’s possible an infection could be the cause of your optic neuritis.
• The MRI detects lesions that could mean you have MS, NMO or MOGAD.
• Your symptoms are more consistent with NMO or MOGAD than MS.

Lab tests generally include blood and urine tests for signs of infection or autoimmune antibodies (especially antibodies that indicate you have NMO or MOGAD). A spinal tap (lumbar puncture) to test your cerebrospinal fluid (CSF) can also detect signs of infection or other changes in your cerebrospinal fluid.

How is optic neuritis treated?

The treatment for optic neuritis generally involves one or two key approaches:

• Intravenous (IV) anti-inflammatory drugs (steroids). Reducing inflammation limits damage to your optic nerve. That should reduce pain and help with vision loss. The standard treatment course is high-dose IV or oral steroids for three to five days. After that, your provider may prescribe lower-dose oral steroids for you to continue taking. (The oral medication dosage gradually decreases, so it’s important to take them as prescribed.)
• Treating any underlying causes or contributing factors. These treatments vary. Examples include antibiotics for bacterial infections, or treatments like plasma exchange (PLEX) to reduce immune system activity if tests show you have an autoimmune disorder like NMO or MOGAD.

Other factors could affect the treatments you receive. Your eye care specialist or other healthcare provider is the best person to tell you more about your options and the likely side effects, complications or other details you should know about.

Is optic neuritis preventable?

Optic neuritis and nerve damage usually happen for unpredictable reasons. There are things you can do to lower your risk, but there’s no way to prevent all possible causes.

The steps you can take include:

• Avoid or quit using tobacco products (this includes vaping and smokeless tobacco products).
• Get infections treated before they can spread to your optic nerves.
• Use prescription medications exactly as recommended and avoid nonprescribed drugs entirely.
• Make nutrition a priority to avoid vitamin deficiencies.
• Practice moderation when it comes to alcohol intake and avoid toxins like methanol.
• Manage existing chronic autoimmune or inflammatory conditions.

What can I expect if I have optic neuritis?

What you can expect with optic neuritis varies depending on the type. Pain and vision loss are common, and these can affect one or both eyes.

Diagnosing optic neuritis can take a few different approaches, and it might feel frustrating while you go through the process. Know that you aren’t alone when this happens. Talking to your provider about your concerns lets them know you need reassurance or encouragement. And it’s always OK to let your eye care specialist or other healthcare providers know you need those kinds of support.

How long optic neuritis lasts

How long optic neuritis lasts depends on the type, the treatments you receive and how well those treatments work.

Typical optic neuritis is usually a short-term concern. The pain from it usually goes away within days (sometimes weeks), and treatment may speed that up. Most people get back clarity, sharpness and color vision over time, too. That can take as little as two weeks or as long as three months.

Atypical optic neuritis tends to be more severe, and the effects usually last longer, especially without treatment. Some people may go for six weeks or more without vision recovery, and it could be permanent, so getting this condition diagnosed and treated quickly is very important.

What is the outlook for optic neuritis?

The outlook for optic neuritis varies, especially when it comes to the form you have:

• Typical optic neuritis. About 90% of people will have normal or near-normal vision after six to 12 months. Long-term vision loss or issues are possible, but they aren’t common. The outcome is usually positive when IV anti-inflammatory treatments start sooner rather than later.
• Atypical optic neuritis. The outlook for this form can vary depending on the specific underlying cause. In general, the outlook is worse when there are delays in treatment.
• Pediatric optic neuritis. The outlook for children with optic neuritis is usually better than for adults. Children are less likely to have long-term impacts from optic neuritis. But, like with adults, there’s still a risk that optic neuritis may be the first warning sign of MS. The 40-year risk of getting an MS diagnosis after having optic neuritis in childhood is about 26%.

Because of the connections between optic neuritis and other conditions, your eye care specialist may refer you to a neurologist, a rheumatologist or both. These specialists can often determine if you have any signs or symptoms of MS or similar conditions now, especially symptoms or signs you might not know to look for. Monitoring you for any changes can help catch those other conditions sooner, which is important because there are treatments that may slow the progress of those diseases.

How do I take care of myself if I have optic neuritis now or had it in the past?

You should see an eye care specialist if you suspect you have optic neuritis. They can begin the initial steps of diagnosing and treating this condition. They can also refer you to a neurologist, rheumatologist or other specialist who might also be able to help treat this condition. The sooner you get a diagnosis and treatment, the better the chances of a favorable outcome.

When should I see my healthcare provider or when should I seek care?

You should always see an eye care specialist if you notice vision loss. If you have sudden vision loss and don’t have a diagnosis for a condition that can cause it, you need emergency medical care right away. If you have a condition that can cause sudden vision loss (like migraines), your eye care specialist or another healthcare provider can tell you more about when it needs emergency medical care.

Once you have an optic neuritis diagnosis, your eye care specialist (and other healthcare providers, if you get a referral to them) will recommend regular follow-up visits. Those visits will help them monitor your condition and symptoms and adjust treatment if necessary.

Does optic neuritis always mean MS?

No, not always. But the risk of developing multiple sclerosis is much higher if you have optic neuritis.

Are there other sources of information about optic neuritis?

Here are some sources of information about optic neuritis:

• National Multiple Sclerosis Society
  www.nmss.org
• North American Neuro-Ophthalmology Society
  www.nanosweb.org