Optic Neuritis: When MS Affects Your Vision

Medically Reviewed by Shruthi N, MD on June 20, 2024
Written by Linda Rath, Shawna Seed
8 min read

When you have optic neuritis, the nerve that sends messages from your eye to your brain, called the optic nerve, is inflamed.

It can happen all of a sudden. Your vision gets dim or blurry. You can’t see colors. Your eyes hurt when you move them. It’s a common problem for people living with multiple sclerosis (MS). The symptoms can seem scary, but most people recover fully, often without treatment.

We don’t know why, but sometimes your immune system attacks the fatty coating called myelin that covers and protects your optic nerve. When the myelin is damaged or missing, your optic nerve can't send the right signals to your brain. This can lead to changes in your vision.

This kind of optic nerve swelling is one of the most common symptoms of the relapsing-remitting form of MS. But it can also happen when you take certain medications or if you have diabetes. It’s also linked to neuromyelitis optica (NMO), or Devic disease. 

Experts divide optic neuritis into categories. 

Typical. This type usually affects only one eye, and it gets better within a few days. Even though it can improve without treatment, you should still have it checked by a doctor. 

Atypical. This type affects both eyes and it doesn't get better quickly. It's linked to neurological problems. 

Pediatric. This type affects children. The outlook for kids with optic neuritis is generally better than it is for adults.

This condition usually comes on quickly, over a few hours or days. You may notice some of these symptoms:

  • Pain when you move your eyes
  • Blurred vision
  • Loss of color vision
  • Trouble seeing to the side
  • A hole in the center of your vision
  • Rarely, blindness in one or both eyes
  • A dull ache behind your eyes
  • Your pupil reacts abnormally when it's exposed to bright light
  • Flashing or flickering lights when you move your eyes

Adults usually get optic neuritis in only one eye, but children may have it in both.

Some people get better in a few weeks, even without treatment. For others, it can take up to a year. And a few people never fully regain their sight. Even when other symptoms clear up, they may still have trouble with night vision or seeing colors.

If you have MS, heat can make optic neuritis symptoms flare up again, too -- usually after a hot shower, exercise, fever, or a bout of the flu. Once you cool off, the problems usually go away.

We don’t know exactly what the cause is. Doctors think it happens when something goes awry in your immune system and it attacks the myelin that covers and protects your optic nerve. The myelin gets inflamed and causes pain. Once it’s damaged, it can’t carry messages from your eyes to your brain.

Optic neuritis has close links to multiple sclerosis. About half the people who have MS will get it. It’s also an early sign of the disease. People with MS usually get the typical type of optic neuritis.

Atypical optic neuritis has been linked to neuromyelitis optica (NMO) and MOG-antibody-associated disease (MOGAD). At one time, researchers thought these two conditions and MS were all the same disease. Now they know that different antibodies are involved.

NMO causes immune system cells and antibodies to attack your optic nerves, spinal cord, and, sometimes, your brain. NMO is more severe than MS and is more difficult to recover from.

When you have MOGAD, your immune system mistakenly attacks the myelin for the nerves in your brain, spinal cord, and eyes. The full name for MOGAD is myelin oligodendrocyte glycoprotein antibody disorder. The outlook for recovery is better with MOGAD than NMO.

Other causes include:

  • Bacterial infections like Lyme disease
  • Viral infections like measles and mumps
  • Autoimmune diseases like sarcoidosis and lupus
  • Toxins such as methanol (also called wood alcohol), alcohol, and tobacco products
  • Fungal infections such as cryptococcosis, histoplasmosis, aspergillosis, and candidiasis
  • Parasitic infections you can get from animals, including toxoplasmosis (cats) and toxocariasis (dogs)
  • Nerve compression that puts pressure on your optic nerve, which can be caused by a tumor or buildup of spinal fluid in your brain
  • Vitamin deficiencies, especially B12
  • Poor blood flow to your optic nerve, called ischemia
  • Metabolic conditions like type 2 diabetes
  • Medications, including some cancer drugs, some drugs for heart arrhythmia, quinine , and some antibiotics

You may be more likely to get optic neuritis if you:

  • Have MS
  • Live at a high altitude
  • Live far from the equator -- experts believe the slightly higher risk is tied to sunlight exposure and vitamin D
  • Are white
  • Are female or were assigned female at birth
  • Are 20-40
  • Have certain genes that raise your odds

Even though optic neuritis symptoms go away, you will probably have:

  • Some optic nerve damage: It may or may not cause symptoms.
  • Vision changes: Your sight should be as sharp as it was before the optic neuritis, but you may not see colors as well.
  • Medication side effects: The steroids most often used to treat optic neuritis put a damper on your immune system. You may get infections more easily. These drugs can also cause mood changes and weight gain. Long-term steroid use also can weaken your bones and raise your blood sugar and blood pressure.

If your general medical doctor thinks you may have optic neuritis, they may refer you to a neurology eye specialist. You'll likely have a routine eye exam to check:

  • Your color vision
  • The smallest letters you can read on a chart
  • Your side, or peripheral, vision

They’ll also use a test called magnetic resonance imaging (MRI). It creates a detailed picture of your brain and helps your doctor look for damaged areas called lesions. They may inject dye into a vein in your arm. It will make your optic nerve and brain easier to see.

Other tests your doctor might use include:

Pupillary reaction test: The doctor will shine a bright light in front of your eyes to see how they respond.

Ophthalmoscopy: It checks your optic nerve to see if it’s swollen.

Blood tests: They can find proteins in your blood that show you might be likely to get, or already have, neuromyelitis optica.

Lumbar puncture: If both eyes are affected, if you’re under 15, or if your doctor thinks you have an infection, they might use this test to check the fluid that surrounds your brain and spinal cord. You might hear them call it a spinal tap.

Optical coherence tomography (OCT): It measures the fiber layer in your retinal nerve. If you have optic neuritis, it’ll be thinner than in people who don’t.

Visual evoked response: The doctor attaches wires to your head with small patches. The wires record your brain's responses as you watch a screen that displays an alternating checkerboard pattern. The test measures the speed at which your optic nerve sends signals to your brain. If it’s damaged, they’ll move more slowly.

Expect to go to back to the doctor in 2 to 4 weeks to confirm the diagnosis.

The condition often goes away on its own. To help you heal faster, your doctor will probably give you high-dose steroid drugs through an IV. This treatment may also lower your risk of other MS problems or delay its start if it’s the cause. But while these drugs help the swelling go down, they won’t make a difference in your vision.

In special cases, your doctor may suggest other treatments, such as:

  • Intravenous immune globulin (IVIG): You may also hear it called plasma exchange. This is a medication made from blood. You get it through a vein in your arm. It’s costly, and doctors aren’t completely sure that it works. But it may be an option if you have severe symptoms and can't use steroids or they haven’t helped you. You can get this treatment long-term if you have optic neuritis and your brain MRI shows you have lesions.
  • Vitamin B12 shots. It’s rare, but optic neuritis can happen when the body has too little of this nutrient. In these cases, doctors can prescribe extra vitamin B12.

If your optic neuritis results from a disease, your doctor will treat that condition.

Once your vision is back to normal, you can get optic neuritis again, especially if you have MS. If your symptoms return, be sure to tell your doctor. Report any new symptoms or those that get worse, too.

If your optic neuritis comes back, you have a higher risk for MS, neuromyelitis optica, or MOG-antibody-associated disease.

This condition is unpredictable and can happen for reasons you can't control. But you can take steps to lower your risk factors. They include:

  • Don't use tobacco products.
  • Drink alcohol in moderation.
  • Get prompt treatment for infections.
  • Follow directions when taking prescription medicine.
  • Avoid street drugs.
  • Eat a balanced diet to avoid vitamin deficiencies.
  • If you have an autoimmune or inflammatory condition, work with your doctor to manage it.

If you have optic neuritis and your doctor sees lesions on your brain, you may want to consider taking medicine to cut your risk of MS. Injectable drugs such as interferon beta-1a or interferon beta-1b might delay MS or help you prevent it.

Optic neuritis is an inflammation of your optic nerve, which sends signals from your eyes to your brain. It can come on suddenly, causing eye pain, reduced vision, and an inability to see colors. It's linked to multiple sclerosis, but other things can cause it as well. You can get it from infections, taking certain medications, vitamin deficiencies, and type 2 diabetes. It may clear up on its own within a week -- especially if only one eye is affected. But you should see a doctor even if your vision clears. Optic neuritis can come back. You may need treatment for an underlying health problem. 

How can I manage optic neuritis at home?

Your eyesight might get worse when you're tired, so make sure you get plenty of rest. Heat also can affect optic neuritis. Exercise, a hot shower, or a fever can heat your body up. If your symptoms get worse while exercising or after a shower, cooling down should improve them. Talk to your doctor about how you should deal with fevers if you've had optic neuritis in the past. 

Can optic neuritis cause permanent vision loss?

Yes. The atypical type is more likely to cause long-term problems. Even if your symptoms improve within a week, you should see a doctor. 

What are the long-term effects of optic neuritis?

For most people -- about 90% -- their vision is nearly back to normal within 6 months to a year. Starting an anti-inflammatory medication early on can boost your chances of a full recovery. Your doctor may want you to see a specialist like a neurologist or rheumatologist to look for underlying illnesses. Getting an early diagnosis and treatment can slow the progression of some diseases. 

Children with optic neuritis are less likely to have long-term effects.