Optic Neuritis: Causes, Symptoms, and Treatments

Medically Reviewed By Vicente Diaz, MD, MBA
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Optic neuritis (ON) occurs when the optic nerve becomes swollen. This inflammation can cause temporary vision issues and pain The optic nerve plays a vital role in your ability to see. This bundle of nerve fibers carries visual signals from the eye to the brain. An inflamed optic nerve causes unilateral visual loss, which impacts the eye’s ability to perceive light.

Vision loss can occur in one or both eyes. It is usually temporary and may occur suddenly or gradually. Researchers estimate that the rate of new ON cases is around 0.5–5.6 per 100,000 people annually.

Keep reading to learn more about the causes, symptoms, diagnostic process, and treatment options for optic neuritis. 

What are the causes of optic neuritis? 

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Experts are unsure about exactly what causes optic neuritis (ON). However, the Genetic and Rare Diseases Information Center (GARD) states that certain factors may play a role in the onset, including:

  • Autoimmune conditions: Researchers believe an autoimmune reaction can cause damage to the optic nerve’s protective layer, resulting in ON. Autoimmune conditions, such as lupus, sarcoidosis, and Sjögren’s syndrome, may trigger ON. 
  • Viral illnesses: Viral illness can cause autoimmune reactions, which may induce ON. Examples include Lyme disease, herpes, HIV, measles, shingles, and meningitis
  • Multiple sclerosis (MS): ON is one of the most common initial symptoms of MS.
  • Drug toxicity: Alcohol, tobacco, carbon monoxide, and lead or mercury poisoning may trigger ON. Medications such as antibiotic, antimalarial, and anticancer drugs can also contribute. 
  • Vitamin B12 deficiency: A 2020 study suggests that people with symptoms of ON may benefit from screenings for vitamin B12 deficiency

What are the symptoms of optic neuritis? 

Optic neuritis (ON) symptoms can occur in one or both eyes. They can develop suddenly or over several days. Symptoms may worsen when your body temperature increases, which is known as Uhthoff’s phenomenon. 

Symptoms can include: 

  • blurred vision
  • dim vision, even in bright lighting
  • dull colors
  • pain in the back of the eye socket
  • pain when you move your eyes

If you experience symptoms of ON, contact your doctor to get a definitive diagnosis.

How do doctors diagnose optic neuritis?

Your doctor may conduct the following tests to confirm a diagnosis of optic neuritis (ON): 

  • a vision exam 
  • automated visual field testing, which measures how far you can see in any direction without moving your eyes
  • color vision testing 
  • a pupillary examination to measure how your pupils respond to light
  • optical coherence tomography, which captures images of your retina

If these test results are consistent with ON, your doctor may order an MRI of your brain and eye sockets. An MRI can help doctors diagnose or rule out MS as a contributing factor. 

Your doctor may also order bloodwork to determine whether a viral illness or vitamin B12 deficiency is causing ON. 

What are the treatments for optic neuritis?

To treat optic neuritis (ON), doctors will typically prescribe corticosteroids to help reduce nerve inflammation. These medications may come in IV or oral form.

Corticosteroids may help speed up your vision recovery. In cases where MS causes the ON, corticosteroids generally do not restore vision to its state prior to the condition’s onset.

In cases where a vitamin B12 deficiency causes the ON, supplementation may prevent permanent eye damage. If a medication or toxic substance causes the ON, doctors may suggest treatments that reduce or prevent exposure to the substance.

After an ON episode, your medical care team will monitor you for recurring symptoms or MS.

What is the outlook for people with optic neuritis?

Most people with optic neuritis (ON) experience symptom relief with corticosteroid treatment. ON-related pain usually resolves within a few days or weeks. Additionally, visual clarity and color perception begin improving after 2 weeks to 3 months.

Nearly 90% of people with ON achieve their previous vision level within 6 months.

In some cases, ON can resolve on its own. However, delaying treatment from a licensed ophthalmologist can result in permanent vision loss. 

What are some potential complications of optic neuritis?

In some cases, optic neuritis (ON) can result in permanent optic nerve damage. This can occur even if the condition does not cause noticeable symptoms. Some people may also experience altered color perception and permanent vision loss.

Additionally, the corticosteroids that doctors often prescribe for ON may cause side effects, including:

What are the risk factors for optic neuritis?

Optic neuritis (ON) may be more common in people who have had recent viral conditions. This includes mumps, measles, or the flu. ON may also be more likely to occur in people with documented autoimmune conditions.

This condition impacts females more often than males (sexes assigned at birth). It occurs most often from ages 20–40 years.

Other frequently asked questions

These are a few other commonly asked questions about optic neuritis (ON). Dr. Vicente Diaz has reviewed the answers.

Is optic neuritis curable?

ON can resolve on its own or through corticosteroid treatment. People with underlying conditions, such as MS, may need additional treatment to manage their ON symptoms.

Can you go blind with optic neuritis?

Vision loss from ON is usually temporary. However, some people may experience some degree of permanent vision loss. Prompt diagnosis and treatment are essential to reducing your risk of vision loss.

How long does optic neuritis take to develop?

Symptoms of ON can develop suddenly or over a few days.

Summary

Optic neuritis (ON) is inflammation of the optic nerve. This nerve is a bundle of fibers that delivers visual signals from the eye to the brain. When the outer layer of this nerve sustains damage, symptoms can occur. These symptoms include blurred vision, pain when moving the eyes, and seeing dull colors.

Doctors diagnose ON using bloodwork and imaging tests, which can also help identify the underlying cause. Treatment often involves taking corticosteroids to reduce inflammation. Most people experience symptom relief with corticosteroid therapy. However, this treatment is less effective in MS cases.

Talk with your doctor if you experience any kind of vision impairment or pain in the eye.

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Medical Reviewer: Vicente Diaz, MD, MBA
Last Review Date: 2022 Aug 24
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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  2. Boyd, K. (2022). What is optic neuritis? https://www.aao.org/eye-health/diseases/what-is-optic-neuritis
  3. Guier, C. P., et al. (2022). Optic neuritis. https://www.ncbi.nlm.nih.gov/books/NBK557853/
  4. Kale, N. (2016). Optic neuritis as an early sign of multiple sclerosis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5398757/
  5. Optic neuritis. (2021). https://rarediseases.info.nih.gov/diseases/7320/optic-neuritis
  6. Yasir, M., et al. (2022). Corticosteroid adverse effects. https://www.ncbi.nlm.nih.gov/books/NBK531462/