Optic neuritis means inflammation (swelling) of your optic nerve. It can affect your vision in the short term, but for most people, the condition normally gets better on its own and doesn’t usually cause any significant lasting loss of vision. Often, the cause of optic neuritis is unknown, and an episode of optic neuritis is not necessarily a sign of another health condition.
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How does optic neuritis affect sight?
Optic neuritis usually causes a reduction or loss of vision in at least one eye, so that your vision becomes blurred, dim, or faded. This change in vision usually comes on over the course of a few days and may continue to worsen over the first two weeks. Optic neuritis usually affects vision in one eye, but in some types, it may affect both eyes.
Optic neuritis commonly affects the central area of your vision, causing it to become blurry and unclear. However, any area of your visual field may be affected. Central vision is the sight you use for reading, watching television, using a computer as well as recognising people's faces and doing close tasks that require detailed vision.
Some people with optic neuritis describe seeing flashing or flickering lights. You may also find that your colour vision is affected. Colours, particularly reds, can appear “washed out” or less bright than usual. In addition, you may notice that you are less able to pick out objects against their backgrounds, particularly if they are a similar shade or colour, for example reading yellow text on a yellow background. This is described as having reduced contrast sensitivity.
Your vision in the affected eye may also temporarily worsen due to heat, for example after a bath, or if you exercise, although this should improve again once you cool down.
When your vision is first affected it’s common to experience discomfort or pain around your eyes, which might get worse when you move your eyes. This pain may be present before the change in your vision, or it may happen at the same time. It will normally only last a few days.
What causes optic neuritis?
The most common type of optic neuritis is “demyelinating” optic neuritis. In most people, the cause of demyelinating optic neuritis is not known. This is called “idiopathic”, meaning that no cause for the inflammation can be found.
Some cases may be “autoimmune”, where the immune system mistakenly attacks healthy tissue, causing inflammation. Certain autoimmune conditions can be associated with optic neuritis including multiple sclerosis (MS), neuromyelitis optica (NMO), myelin oligodendrocyte glycoprotein (MOG), chronic relapsing inflammatory optic neuritis (CRION) and sarcoidosis.
Less commonly, optic neuritis can also be caused by infection (infectious optic neuritis), or as a reaction to how your body's immune system copes with an infection (parainfectious optic neuritis).
Demyelinating optic neuritis
The most common type of optic neuritis is demyelinating optic neuritis. Demyelination is where the protective myelin coating on your nerve fibres breaks down. When your myelin breaks down patches of demyelination, known as lesions, occur. These can slow down or stop the signal being carried by the nerve to your brain. This can then affect your vision.
The reasons why demyelination happens are not clearly understood, but evidence suggests that the body’s own immune system causes the myelin to break down (autoimmune).
Optic neuritis and multiple sclerosis (MS)
There is an association between demyelinating optic neuritis and MS. MS is a demyelinating condition that can affect any part of the central nervous system (CNS). The CNS includes the brain and spinal cord and is responsible for controlling all the functions in our bodies such as balance, movement, emotions, as well as vision. MS can cause a large range of symptoms depending on which part of the CNS has been affected, and these can vary widely from person to person.
If you are diagnosed with demyelinating optic neuritis, your ophthalmologist may discuss the possibility that this could be linked to MS. There is evidence that people who have an acute episode of demyelinating optic neuritis have a 38 per cent risk of going on to develop MS within 10 years. However, it is important to remember that not everyone who has acute demyelinating optic neuritis will be diagnosed with MS or will develop MS in the future.
Recovering from optic neuritis
For many people with optic neuritis, vision typically gets worse over a period of several days to two weeks and then begins to improve.
Optic neuritis usually gets better on its own. A large-scale study, the Optic Neuritis Treatment Trial (ONTT), looked at the best way to treat optic neuritis in nearly 400 people. This trial found that regardless of whether treatment was given or not, over 90 percent of the people they followed for the study had an improvement in their sight within the first month from when vision loss began.
What treatment will I need?
Not everyone with optic neuritis requires treatment. The treatment a person may require depends on the type of optic neuritis they have, as well as how it is affecting them.
If you are experiencing discomfort or pain because of optic neuritis and this is very uncomfortable, your GP or ophthalmologist will be able to advise you about pain relief. It may be possible to improve things with over-the-counter pain medications. This pain or discomfort will normally only last for a few days.
If needed, treatment for the most common demyelinating type of optic neuritis is high dose steroids which may be given intravenously or in oral tablet form. Intravenous steroids are usually given for three to five days, for which you would need to be admitted to hospital. Sometimes this is followed by oral steroids. The dose of the tablets is slowly reduced. The period of reducing oral steroids (also called oral taper) can vary from one week up to six months. It is very rare for steroids to be required for longer than this.
If your vision is severely affected by demyelinating optic neuritis, steroid treatment may speed up recovery by a week or so, however, studies have found that this treatment makes no difference to how well your vision recovers in the long term. Therefore, the small benefit from this treatment would need to be weighed against the risks and side effects of taking high dose steroids. This means that most people with optic neuritis will not have steroid treatment.
However, if you have a rarer type of optic neuritis such as MOG, CRION or NMO, then steroid treatment can help to improve the visual recovery.
Steroid treatment may also occasionally be given if someone has poor vision in the other eye, if the symptoms are particularly severe or distressing, or if the change in vision impacts on activities which may be essential for someone's job, for example, driving.
Some of the rare types of optic neuritis such as MOG, CRION and NMO may also require treatment with medication to control the immune system. Some people may need this treatment long term to reduce the risk of another attack of optic neuritis. Your ophthalmologist will explain whether this form of treatment is required, based on the type of optic neuritis you have been diagnosed with.
If your optic neuritis is caused by an underlying infection, then you may need treatment with antimicrobial or antifungal medication. Your ophthalmologist would be able to discuss what course of action would be best for you.
What about the long term?
The initial improvement in vision happens as inflammation goes down and your optic nerve begins to recover. Recovery of your vision can happen quickly at first but may then slow down. Your vision may continue to improve over a period of six months to a year and by about nine to twelve months it’s likely to be clear what the final recovery of your vision is.
It may be difficult to predict what your vision will be like in the long term. If this is the first time you have had optic neuritis, your sight should make a good recovery, even if your vision is quite severely affected to start. Most people diagnosed with the more common type of optic neuritis, acute demyelinating optic neuritis, will make a very good long term visual recovery.
Following an episode of optic neuritis, the ophthalmologist or optometrist may be able to see some lasting damage to the optic nerve when they examine the back of your eye or take an OCT scan. This lasting damage is known as “optic atrophy”.
For some people this might mean that after an initial improvement they can still be left with some permanent visual changes. These can include colours appearing faded and reduced contrast sensitivity.
You may also notice that your vision isn't as sharp as it used to be and/or that you struggle with your perception of depth or movement. These symptoms can be present even if your central vision is good on the letter chart when tested by your ophthalmologist or optometrist.
More rarely, some people may not experience a great deal of improvement in vision and be left with reduced vision even after the inflammation has settled.
Will I get optic neuritis again?
If you’ve had optic neuritis once, there is some risk that it may occur again in either eye. For demyelinating optic neuritis, the ONTT found that 28 per cent of people had another episode within five years, and this went up to 35 percent of people within 10 years. However, this does mean that 65 per cent of people (more than half) had not experienced any further episodes of optic neuritis within 10 years.
It may not be possible to predict whether you will experience further episodes of optic neuritis. However, you may wish to explore this with your ophthalmologist, as they may be able to give you more information based on your medical history and whether this is the first time you have had optic neuritis.
Most people with optic neuritis make a good recovery of their vision and do not have any long-term problems with their sight. A few people may be left with some permanent changes to their sight, but much can be done to help you make the most of your remaining vision and adapt to any changes.
If both your eyes have been affected, or if the affected eye was your good eye and you have a sight problem in your other eye, then you may need to make changes or use aids to make the most of your remaining sight. This may mean making things bigger, using brighter lighting, or using colour and contrast to make things easier to see. You should ask your ophthalmologist, optometrist or GP about low vision aids and getting a low vision assessment. During this assessment with an optometrist, you’ll be able to discuss the use of magnifiers and aids to help you to see things more clearly.
You can also find out tips for making the most of your sight by downloading our booklet:
Page last reviewed: Sept. 1, 2022
Next review due: Jan. 31, 2023