Nystagmus

Overview

Nystagmus is an uncontrolled movement of the eyes, usually from side to side, but sometimes the eyes swing up and down or even in a circular movement.

Most people with nystagmus have vision which is worse than average.

Nystagmus that appears in the first months of life is called ‘early onset nystagmus’ or ‘congenital nystagmus’. The condition may also develop later in life when the term ‘acquired nystagmus’ is used.

Causes

Nystagmus in early childhood may be caused by a defect in the eye or the visual pathway from the eye to the brain. It occurs in a wide range of eye disorders of childhood such as cataract, glaucoma, some disorders of the retina and albinism (see Related eye conditions below). It may also be found in children who have multiple disabilities such as Down’s syndrome.

Many children with nystagmus do not have eye, brain or other health problems. In this case the condition is called ‘congenital idiopathic nystagmus’ or ‘idiopathic nystagmus’, meaning that the condition starts very early on in life and the cause is unknown.

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. A clinical geneticist can provide detailed information. Your eye specialist will be able to refer you to one. Acquired nystagmus, which develops later in life, may be a symptom of another condition such as stroke, multiple sclerosis or even a blow to the head. There are many causes. Nystagmus is not infectious or contagious.

Because nystagmus may be the first sign of 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.

It is not known accurately how common the condition is, but nystagmus is believed to affect around 1 in 1,000 individuals.

Symptoms

Nystagmus affects people in many ways and the effects vary from person to person. In all cases, the vision will be blurred. Here are some of the ways the condition can affect people.

Most people who have had the condition since childhood are not affected by a constantly moving image (known as ‘oscillopsia’), as their brain adapts to the movement of the eyes. However, people who acquire nystagmus later in life are unlikely to adjust so well and will be affected much more by oscillopsia. Nystagmus is often associated with reduced sight. The degree of sight loss varies from mild to very poor vision and is related to the underlying condition. Many people with the condition are eligible to be registered partially sighted or blind.

Please note that very few people who are registered are totally blind. Most have very poor vision.

Vision varies during the day and is likely to be affected by emotional and physical factors such as stress, tiredness, nervousness or unfamiliar surroundings. People with nystagmus may tire more easily than other people because of the extra effort involved in looking at things.

Many people with nystagmus can read very small print if it is close enough to their eyes. Some find a visual aid such as a magnifier helpful. However, large print material should always be made available and all written matter should be clear. It is very difficult to share a book because it will probably be too far away or at the wrong angle.

People with nystagmus may be slow readers because of the extra time needed to scan. This should not be taken as a sign of poor reading ability, but students or school children with nystagmus may need extra time studying and when sitting exams.

Many people with nystagmus use computers, as they can position screens to suit their own needs and adjust brightness, character size, and so on. However, some people find it difficult to read computer screens for more than a few minutes. Experimenting with different colour combinations and using large screens may help. The angle of vision is important. Many people with the condition have a ‘null point’ where the eye movement is reduced and the vision is improved. They will often turn their head to one side to make the best use of their vision. Sitting to one side of a screen or blackboard often helps. Children with nystagmus should be allowed to adopt the head posture which gives them best vision.

Uncontrolled head nodding helps concentration probably because the head movement compensates somewhat for the eye movement.

Depth perception is usually considerably reduced. This may sometimes make people seem a little slower or clumsier than normal.

Balance may be affected, possibly because of poor depth perception, which may make it difficult to use stairs or cross uneven surfaces.

Confidence may be reduced because of poor vision and maintaining eye contact may be difficult.

Getting about can also be affected, especially in unfamiliar and busy surroundings such as supermarkets, railway stations and airports. Crossing roads is more difficult too. Orientation (knowing where you are) and mobility (moving from place to place safely) training can help. Very few people with nystagmus are legally able to drive a car.

Treatments

Nystagmus cannot be cured but there are several treatments which can help.

Glasses and contact lenses do not correct nystagmus although they may help a little and should certainly be worn to correct other sight problems. A child or adult may be diagnosed as being ‘short sighted’ or ‘long sighted’ as well as having nystagmus. Long or short sightedness occurs because the eye itself is not exactly the right shape for focusing.

The focusing problems can be corrected with glasses or contact lenses, but the nystagmus will still affect the person’s eyesight. Being long sighted does not mean that someone with nystagmus has good distance vision. Ask your ophthalmologist or optician to explain more.

Very occasionally, surgery is performed to alter the position of the muscles, which move the eye. The purpose of this is to reduce the amount the head has to turn to try and see better.

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. For example, the patient might listen to an electronic signal, which goes higher when the eye movement is greater. Some people have said that they benefit from this type of treatment.

However, the evidence is not conclusive and many of questions remain unanswered such as: “Do these techniques bring about a real improvement in vision and do the possible effects last?”

The good news is that nystagmus is not painful and does not lead to total blindness. Vision tends to improve until it stabilises 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. Toys which encourage the child to follow a moving object, such as marbles or train sets, are helpful. So are games which are designed to develop hand-to-eye coordination.

It is not possible to say which type of school is best for the child with nystagmus – each child has his / her special requirements. However, most children with nystagmus go to mainstream schools. Many go on to college and most adults lead fulfilled, independent lives.

How can the effects be minimised?

Much can be done to reduce the effects of nystagmus and make sure that people with the condition have the same access to the same opportunities as fully sighted people.

Accurate information and support, during the early years in particular, can and do 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.

Related eye 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 and usually in the skin and hair as well. This causes most people with albinism to have a very fair, almost white, appearance, although in some people albinism affects the eyes only. People with albinism find their greatest problems arise on sunny days and in brightly lit environments. Virtually everyone with albinism has nystagmus.

Cone dystrophy

Cone dystrophy is an impairment to vision which can be caused by any one of a number of eye disorders. These disorders may or may not be inherited. Some dystrophies appear later in life, sometimes as late as 50. Other types may appear in early childhood or even be present at birth. Cone dystrophy may cause problems with seeing in bright light, seeing detail 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. Not all cataracts impair sight so badly that an operation is required. 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 some cases the cause cannot be identified.

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. Nystagmus is a common side effect of Down’s syndrome.

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