Nystagmus

Nystagmus is continuous, uncontrolled to and fro movement of the eyes - find out more about its causes, symptoms and treatment

About nystagmus

Nystagmus is continuous uncontrolled to and fro movement of the eyes. The movements may be in any direction. This means that the eyes will look like they are moving from side to side or up and down or even in circles. Most people with nystagmus have reduced vision.

Nystagmus is a sign of a problem with the visual system or the pathways that connect the eyes to the parts of the brain that analyse vision. These parts of the brain deal with eye movement. It is not really a condition in its own right.

Some types of nystagmus happen when your eye gaze positions are extreme, when you looking far to the left, right, up or down and are a natural part of the way the eye and brain work together. Nystagmus which happens when your eyes aren't in these positions is usually is a sign of a problem.

There are two main types of nystagmus, one which appears in the first months of life which is called "early onset nystagmus" or "congenital nystagmus" and another which develops later in life which is usually called "acquired nystagmus". In many cases the cause of the nystagmus will not be known. Nystagmus is believed to affect between one in 1,000 and one in 2,000 people.

How your eye works

When you look at something, light passes through the front of your eye, and is focused by the lens in your eye onto the retina. The information then passes along the visual pathway to the different parts of the brain that allow us to see things. Different parts of the brain send signals back to your eye to control different aspects of how the eye works. Where your eyes focus, the size of your pupil and your eye movements are constantly being controlled and adjusted to give us the best vision possible. Mostly you are unaware of your eye and brain doing this.

Causes

The eye movement seen in someone with nystagmus can also sometimes be seen in people without nystagmus. The movements used by a healthy visual system (the way the eye and the brain work together to produce sight - a tracking system) are in certain situations the same movements seen in someone with nystagmus. For example if you watch someone's eyes as they are watching a train passing, their eyes follow the train then flick back to a starting point and this is repeated over and over until the train has passed. This type of nystagmus is called "physiological nystagmus", and it is a normal part of how our eyes work.

If the visual pathways, or parts of the brain that process visual information, or parts of the brain that control eye movements or gaze does not develop properly, or is damaged in later life then eye movements can become poorly controlled and this is called nystagmus (short for "pathological nystagmus").

Congenital Nystagmus

Congenital nystagmus simply means nystagmus that is noticed in very young children, usually soon after they're born or sometimes in the first couple of years of their life. This type of nystagmus can be caused by two things either a problem with the eye itself or with a problem with the visual pathway from the eye to the brain.

All children are born with a visual system that is not fully developed. Our vision continues to develop in the first few years of life as a result of the eye and brain being stimulated by what we see. If a child is born with an eye condition which affects vision such as cataract, glaucoma, some conditions of the retina and albinism then their visual system may not develop normally. This is because these conditions lower the amount of visual stimulation the eye and brain receive.

Reduced visual stimulation can affect the development of the control of eye movement and if this happens the child will have nystagmus. The severity of the congenital nystagmus often depends on the severity of the sight loss caused by the underlying condition.

Children who have learning disabilities, such as Down's syndrome, may also develop nystagmus. Nystagmus can also be caused by some inherited neurological conditions.
However, many children with nystagmus do not have any obvious eye, brain or other health problems even though they appear to have nystagmus. This type of nystagmus is called "congenital idiopathic nystagmus" or "idiopathic nystagmus", meaning that the condition starts very early on in life and the cause is unknown. In idiopathic nystagmus the vision is also reduced.

Nystagmus is not painful and does not lead to progressive loss of vision. Problems resulting from congenital or early onset nystagmus tend to improve until vision stabilizes around the age of five or six. Giving children plenty of stimulation in the early years does seem to help them make best use of the vision they have.

It is not possible to say which type of school is best for a child with nystagmus - each child has their own special requirements. However, most children with nystagmus go to mainstream schools. Many go on to college and most adults with nystagmus lead independent lives.

Acquired nystagmus

Nystagmus that develops later, generally in adults, is called "acquired nystagmus". Often acquired nystagmus is a sign of another (underlying) condition such as stroke, multiple sclerosis, brain tumour, the effect of a drug or a head injury. Anything that damages the parts of the brain that control eye movements can result in nystagmus.

Describing how your eyes move

Neurologists and ophthalmologists sometimes classify nystagmus by a description of how the eyes move. For example, "jerk nystagmus" describes nystagmus where the movement is quick in one direction and slow in another and nystagmus is described as "pendular" if the movement is slow in all directions. The direction of the nystagmus is also recorded as vertical, horizontal or circular. Direction and type of movement may vary depending on where someone looks and how calm they are feeling.

This way of classifying nystagmus is used because the nature of the eye movements gives the specialist an indication of what is causing the problem. If you are unclear about how your nystagmus has been described, you can ask the specialist to explain it to you.

Symptoms

Because nystagmus is a sign of so many different underlying causes, the way that vision is affected is very varied.

If you have congenital nystagmus, how much your vision is affected depends on the underlying condition. Some people will be able to read most sizes of print without help, while others may have vision that makes them eligible to be registered as severely sight impaired (blind) or sight impaired (partially sighted). Being registered as severely sight impaired/blind does not necessarily mean that you are totally without sight, or will lose all your sight in the future.

The degree or severity of nystagmus may vary according to direction of gaze, near or distance fixation. Most people with nystagmus find that their vision is very variable. The vision tends to worsen when the eye movements or amplitude of the nystagmus increases. This is often linked to how stressful they are finding a situation. The more stressful a situation, the worse the vision would be.

Most people with nystagmus find that they have a particular head position that results in the slowest movement of the eyes. This is known as the "null point". This reduction in the movement or amplitude of the nystagmus usually means the vision improves. Some people with nystagmus also find that nodding their heads helps improve their vision.

For reasons that are not fully understood, people with congenital nystagmus only very rarely see the world constantly moving. By contrast, people who develop nystagmus later in life (acquired nystagmus) are usually aware of constant and sometimes very disabling movement. This awareness is called oscillopsia. This is probably because their brain has not adapted to the unexpected eye movements and sees instead the world moving around. This is very disabling and early treatment is aimed at controlling this problem.

Because each case of nystagmus is individual, each person needs a detailed assessment.

Investigation

Because nystagmus may be the first sign of a serious disorder of the eye or the brain, it is vital that when nystagmus first develops the child or adult is referred to an ophthalmologist (eye specialist) or a neurologist.

The investigations depend on the type of nystagmus, your age and what your doctor feels is the underlying cause. For a baby or young child with congenital nystagmus, the focus of the investigations and treatment will be on maximising the child's visual development.

It is very likely that an ophthalmology clinic will monitor the condition and this may mean seeing a number of different professionals. The ophthalmologist is the specialist eye doctor who is responsible for the case overall and would carry out any treatments. An orthoptist specialises in assessing eye movements and may be used to assess in detail the way the eyes are moving. An optometrist specialises in making sure glasses and contact lenses are correct but would also carry out a low vision assessment.

Measuring vision

The eye clinic can investigate your vision in a number of different ways. Different tests are used to assess how well we see detail, faint edges, peripheral detail and colour. There are specially adapted tests for children of different ages.

The most common test is the visual acuity test which is the familiar set of letters on a chart held six metres away. Many people with nystagmus manage to read down quite far on this test especially if they are calm and can use their null point. They then feel that the result gives a false impression of how well they can see. This is because the test does not reflect well the real world where objects move, lighting changes and we can become anxious. All of these factors make the vision worse.

If your vision is variable, make this clear to the specialists testing you. Give examples of situations when your vision is at its worse such as trying to find the right platform for a train if you are running late. Any official reports on your vision need to reflect the fact that your vision is variable.

Low vision assessment

This assessment looks at ways to help you make the most of your vision by choosing appropriate lighting, making adaptations, such as colour contrast, as well as using magnifiers or technology to make things easier to see. It is an ideal opportunity to discuss any practical problems you are having with your vision.

A low vision assessment should help you understand what you can see in different conditions and what resources or alternative methods you can use. It should include practical help such as magnifiers to enable you to read.

Ideally, if you have reduced vision due to nystagmus, you should see a low vision service once a year. This is especially important for children and the ideas from the assessment should be reported back to school, with time built in for the child and staff to learn how to use any special equipment.

Investigating the null point

As part of any assessment the specialists will investigate and try to identify your "null point". The null point is the position of the head that results in the slowest movement of the eyes. This reduction in the movement or amplitude of the nystagmus usually means that you are able to see more easily. Identifying the null point for someone with nystagmus, especially a child, is very useful. Teachers may need to be told that it does no harm to hold the head in an unusual way and that a child should adopt the head posture which gives the best vision.

Genetic counselling

Several types of nystagmus can be inherited. To find out the chances of someone passing on nystagmus to the next generation, a specialist must first make an accurate diagnosis of the underlying condition. Your eye specialist can refer you to a clinical geneticist who can provide detailed information.

Information sharing

Accurate information and support, during the early years in particular, can and does make a big difference. In the worst cases, without a clear explanation of the effects of nystagmus, some children are mistakenly thought to have learning difficulties. This means that the real problems caused by their poor vision are not addressed. With the support of teachers trained in visual impairment, an understanding school and the help of parents, most of the difficulties presented by nystagmus can be overcome. As a parent you need to ask that reports are sent after hospital assessments to your children's school, using wording that can be understood by everyone.

You may have many questions that you would like your eye clinic team to answer. For example, will my vision get worse? How do I best use my vision? Can my nystagmus be treated? Thinking about the questions you want answered before your clinic appointment and writing them down is often very useful. Do not be afraid to ask for a clear explanation of things you have not understood about your or your child's nystagmus.

Treatments

Nystagmus cannot be cured. Some underlying conditions may be treatable which may affect the nystagmus. Researchers around the world are looking at different aspects of nystagmus with the aim of developing treatments. A lot of this work still focuses on how the eye movements are controlled and our understanding of this is far from complete. Not all the treatments you may read about are backed up by good clinical evidence. The Nystagmus Network website produces authoritative updates on current research work in the field.

Glasses, contact lenses and low vision aids

Glasses and contact lenses ensure that vision is corrected and that you are getting the most from your vision. They do not correct nystagmus although having clearer vision can help slow the eye movements. Special magnifiers called low vision aids can help with reading and tinted glasses may be useful to control glare. A low vision assessment will look at using these types of devices.

Surgery

Very occasionally, surgery is performed to alter the position of the muscles which move the eye. This is to reduce the amount the head has to turn to get to the null point, making it more comfortable to keep your head in the best position. However, surgery cannot correct or cure nystagmus. Work is being done to see if surgery to the eye muscles can correct the nystagmus itself but this research is in its early stages.

Drugs

Sometimes drugs are used in the treatment of some acquired nystagmus, for example for someone with multiple sclerosis who develops nystagmus. The drugs help to control the eye movements and reduce the person's awareness of the constant eye movement. This is a very specific type of treatment and is not yet widely used to treat congenital nystagmus. Research is being done into how drugs that affect eye movements might be used to help people with long-standing or congenital nystagmus.

Bio feed back

Researchers have explored ways of trying to reduce the nystagmus by making the patient aware of the eye movement and encouraging them to control it. These techniques rely on visual and audio signals (known as biofeedback) to the patient. One approach, Intermittent Photopic Stimulation (IPS), did not show clear improvements when trialled. There is no clear evidence that any bio feedback works but some people with nystagmus have reported good results.

Related eye conditions

It is important to remember that many children with nystagmus do not have eye, brain or other health problems. However in a small number of cases nystagmus can be related to other conditions.

Albinism

Albinism is the name given to a group of inherited conditions in which there is a lack of pigmentation (colour) in the eyes (ocular albinism) and often in the skin and hair as well. People with albinism find their greatest problems arise on sunny days and in brightly lit environments. Virtually everyone with albinism has nystagmus. The Albinism Fellowship provides information and support to everyone affected by Albinism.

Cone dystrophy

Cone dystrophies are a group of conditions that cause a reduction in vision. Some cone dystrophies are inherited and some appear later in life, sometimes as late as 50. Other types may begin in early childhood or be present at birth. Cone dystrophy affects central vision and can cause problems with seeing in bright light, seeing detail such as watching TV, reading, writing or sewing and seeing colours.

Childhood (or "juvenile") cataract

Cataract is a clouding of the lens of the eye which causes sight to become blurred or dim, because light cannot pass through to the back of the eye. Some babies are born with cataracts and some develop them later in childhood. Childhood cataract may be inherited or may be caused by injury or illness. However, in most cases the cause cannot be identified. Cataracts in children can be removed by surgery, but every cataract is different. The decision to remove childhood cataracts may depend on a number of things, such as the age of the child and how badly the cataracts are affecting sight.

Down's syndrome

Down's syndrome is a genetic condition caused by the presence of an extra chromosome. People with Down's syndrome have 47 chromosomes instead of the usual 46. It is amongst the most common forms of learning disability. People with Down's syndrome often have nystagmus and many also have other eye conditions. They should have their sight checked regularly by an optometrist who has some experience of testing people with learning disability. The Down's Syndrome Association produces information on eye problems that people with Down's syndrome may develop.

Coping

If you or your child is diagnosed with an eye condition it can be very upsetting. You may find that you are worried about the future and how you will manage with the change in vision. All these feelings are natural. RNIB can help with our Helpline and our emotional support service.

Having nystagmus can cause serious changes to vision but there are lots of things that you can do to make the most of your remaining vision. This may mean making things bigger, using brighter lighting or using colour to make things easier to see. Ask your ophthalmologist, optician or GP to refer you to your local low vision service, which can provide you with magnifiers to help with reading and advice on lighting to help make the most of your sight.

If your vision is impaired, it is also worth asking your specialist to help you register as "sight impaired" or "severely sight impaired". This opens the door to expert help and some financial concessions.

Local social services should also be able to offer you information on staying safe in your home and getting out and about safely. They should also be able to offer you some practical mobility training to give you more confidence when you are out.

Our Helpline can also give you information about low vision clinics and the help available from social services . They can also offer advice if you have any difficulties accessing these services and our website offers lots of practical information about adapting to changes in your vision and products that make everyday tasks easier.

Useful contacts

Royal National Institute of Blind People
105 Judd Street, London WC1H 9NE
Tel: 0303 123 9999
helpline@rnib.org.uk
www.rnib.org.uk

Royal College of Ophthalmologists
17 Cornwall Terrace, London NW1 4QW
Tel: 020 7935 0702

Nystagmus Network
Tel: 0845 634 2630

Albinism Fellowship
Tel: 01282 771900

Down's Syndrome Association
Tel: 0845 230 0372

Driver and Vehicle Licensing Agency (DVLA)
Drivers Customer Services (DCS)
Correspondence Team DVLA
Swansea SA6 7JL
Tel: 0300 790 6801

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This information has been produced jointly by the Royal College of Ophthalmologists and Royal National Institute of Blind People, a certified member of the Information Standard.

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© RNIB and RCOphth September 2010

 

This information has been produced jointly by the Royal College of Ophthalmologists and Royal National Institute of Blind People, a certified member of the Information Standard.

© RNIB and RCOphth

 

 

Eye Health Information Disclaimer
This information has been produced jointly by the Royal College of Ophthalmologists and Royal National Institute of Blind People, a certified member of the Information Standard.


 

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