Optic neuritis

Optic neuritis is the name for inflammation of the optic nerve. This is the nerve that carries messages from the eye to the brain.

Although optic neuritis is associated with MS, not everyone who has optic neuritis will have, or go on to develop, MS. Many people will have optic neuritis with no further symptoms.

About optic neuritis

The effects of optic neuritis on your sight can vary. It can range from blurred vision to a complete loss of sight. It often affects just one eye, although it can affect both, either at the same time or one after another.

Optic neuritis can cause any of these symptoms:

  • blurred vision
  • a blind or blurred spot in the middle of your vision
  • changes to how you see colours. They become darker or ‘washed out’, especially reds
  • flashes of light when you move your eyes (called ‘phosphenes’)
  • for a while you might not be able to see through your eye to some degree (or maybe completely)

With optic neuritis, your eyesight tends to get worse over a few days to a week. For some people it can come on much quicker – in a few hours or overnight.

In some cases optic neuritis can be painful, particularly when you move your eyes. The pain usually lasts for a few days, and shouldn’t be severe enough to affect your sleep. If it does, there might be something else causing it.

Optic neuritis is usually diagnosed by an ophthalmologist or neurologist. To reach a diagnosis, they’ll want to know:

  • how your vision is affected
  • when your symptoms came on
  • whether you’ve had any previous neurological symptoms

They might need to carry out some tests, including:

  • a blood test
  • an MRI scan
  • an OCT scan of the eye
  • a visual evoked potential test

MRI scan (magnetic resonance imaging)

You might have an MRI scan to look for inflammation in your optic nerve. This is painless but the MRI scanner can be noisy and you might feel a bit claustrophobic. Ear plugs help, and you can be given something to relax you.

OCT scan (optical coherence tomography)

An OCT scan looks for changes at the back of the eye. It also looks at the optic nerve where it joins the eye. It’s a painless test that uses light to make a 3D picture of your eye. It only takes a few seconds to test each eye. OCT scanners are common at opticians, to check eyes are healthy.

A visual evoked potential test

This is a painless test where you watch patterns on a screen and it measures how fast messages go from your eye to your brain.

It can take up to an hour to do the test. You might not need a visual evoked potential test if you have an OCT scan.

Tests for other eye conditions

Other eye conditions can look like optic neuritis, so, depending on your symptoms, you may need to have further tests. This is more likely if your symptoms aren’t typical, for example:

  • if you have very severe pain that disturbs your sleep or limits how much you can move your eyes
  • if you lose your sight completely in the affected eye
  • if both of your eyes are affected
  • if your sight hasn’t started to improve after three or four weeks

Further tests

If this is your first MS-like symptom, you may also be referred to a neurologist for further tests, including an MRI scan of your brain.

Read more about the tests for MS

Optic neuritis will often improve on its own, usually within a few weeks, so you might not need any treatment.

But that doesn’t mean you should leave an eye symptom days or weeks before having it checked. Always get a problem looked at straight away so you can check what the cause is and get the right treatment.

Steroids to treat optic neuritis

You might be offered steroids if your optic neuritis symptoms are especially bad. For example, if you can’t work properly or drive.

Usually, you’d be given steroids as tablets to take at home. Sometimes they’re given as an infusion (known as a ‘drip’).

Steroids dampen down inflammation in your optic nerve.

Whether you take them or not makes no difference to how good your final recovery will be. But they do speed up how fast your symptoms will ease off.

Read more about steroids

Most people’s sight recovers well from optic neuritis. Given time it often goes back to normal.

In the first three weeks, about 8 in every 10 people start to get better. And within five weeks, around 9 in every 10 people have started to get better.

In the longer term

It could take longer to make a fuller recovery.

Up to a year

Up to a year afterwards your sight might still be getting better.

Around 6 in every 10 people still find they have some mild disturbances in their vision up to a year later.

After 5 years

Five years later, most patients’ sight is good or excellent. That’s true even if they have another bout of optic neuritis during that time. Around half of people with MS who get optic neuritis will get it again within five years.

Small, lasting changes

For between 1 in 10 and 1 in 20 people, their sight never gets back to exactly how it was. So you might notice small, lasting changes.

You might find it harder to pick out colours, or tell the difference between some colours.

Things might not be as sharp as before. Or you might be less good at judging what you see at a distance.

After optic neuritis, your vision can change a little from one day to the next. Fatigue can make it worse. Your eyesight might get worse when you get hot, too. This could be after exercise, a hot bath or shower, or when your temperature goes up during an infection. It happens because nerves find it harder to pass on signals when your body’s hot. Your sight should get better when you cool down.

What if my sight doesn’t get better?

For some people the damage to their optic nerve leaves them with eye problems that don’t go away. Health and social care professionals can help find ways to manage sight problems.

Read more about living with sight problems