Eye Conditions

Medical Information on West Syndrome

For whom is this information intended?

The information contained in this document is intended for use primarily by parents, other members of the family and older children with visual impairment. The information will also be of use to interested health professionals, carers and teachers.

The purpose of each information document

The purpose of the information is to explain:

• The way the eyes and brain normally work to make 'vision'
• The reason why vision may become impaired by a specific condition
• The cause of the condition
• The effects of the condition on the child's vision
• How the condition is diagnosed
• What can be done to help

This document is written with the minimum use of medical terms and jargon. It is impossible to avoid all medical terms but where we have used them we have attempted to explain them as clearly as we can. Although the information is intended to describe most aspects of the condition each child is different and there will always be exceptions to the rule. As far as we can determine these pages are true and accurate and have been written in good faith. Inevitably there will be some mistakes. We apologise for this.

What this information is not for

This document is not a substitute for a consultation with a Health Professional. It should not be used as a means of diagnosing a condition.

We hope the information will help you

After reading the information we hope you will:

• Have a better understanding of the condition
• Know what tests and treatments are normally available
• Know when to seek professional advice
• Be able to discuss the condition in a more informed way
• Make the most of consultations with carers, teachers and health professionals
• Be reassured and more able to cope

Who wrote these documents?

These pages are the consensus of opinion of many different people. They include parents of visually impaired children, visually impaired children themselves, Community Paediatricians, Ophthalmologists, Educationalists and Psychologists.

The main author and person responsible for their content is Dr Andrew Blaikie who is an Ophthalmology Research Fellow with Visual Impairment Scotland and a member of the Royal College of Ophthalmologists. We are very keen that parents and children feedback to VI Scotland about these information documents. If you have any questions or comments regarding the information please contact:

Visual Impairment Scotland
Scottish Sensory Centre
The University of Edinburgh
Holyrood Road
Edinburgh EH8 8AQ

Telephone Number : 0131 651 6078
Fax Number : 0131 651 6502
Textphone : 0131 651 6067

Email : viscotland@ed.ac.uk
Website : www.viscotland.org.uk

Medical Information on West Syndrome

What we see is made in the brain from signals given to it by the eyes.

What we see is in fact made in the brain. The brain makes sight from signals given to it by the eyes.

What is the normal structure of the eye?

The eye is made of three parts.

• A light focussing bit at the front (cornea and lens).
• A light sensitive film at the back of the eye (retina).
• A large collection of communication wires to the brain (optic nerve).

A curved window called the cornea first focuses the light. The light then passes through a hole called the pupil. A circle of muscle called the iris surrounds the pupil. The iris is the coloured part of the eye. The light is then focused onto the back of the eye by a lens. Tiny light sensitive patches (photoreceptors) cover the back of the eye. These photoreceptors collect information about the visual world. The covering of photoreceptors at the back of the eye forms a thin film known as the retina. Each photoreceptor sends its signals down very fine wires to the brain. The wires joining each eye to the brain are called the optic nerves. The information then travels to many different special ‘vision’ parts of the brain. All parts of the brain and eye need to be present and working for us to see normally.

What is West Syndrome?

This is a condition where young children, usually less than 18 months of age develop fits. The child may develop more slowly than expected and have learning difficulties when older. This condition is often also known as ‘Infantile Spasms’. This is because infants develop the condition and the fits appear as spasms of the neck, arms and legs. The condition is called West Syndrome after a Dr West who was the first to describe the condition (in his own son).

What causes West Syndrome?

There is no single cause for West Syndrome but instead many different causes. Normally the movement of a child’s arms and legs are controlled by tiny electrical signals in special parts of the brain. The spasms and fits seen in West Syndrome are due to extra uncontrolled electrical signals from the brain. This happens because parts of the brain:

• May not have developed correctly in the womb or
• Have been damaged around the time of birth or
• Damaged after birth in the early part of life

Performing a head scan can often help tell if a brain abnormality is present. Measuring electrical signals coming from the brain is also helpful. The pattern of signals can help confirm the diagnosis of West Syndrome.

Sometimes no cause can be identified despite lots of tests being done.

Why do children with West Syndrome also have visual impairment?

What we see is in fact made in the brain. The brain makes sight from signals given to it by the eyes. Children with West Syndrome have visual difficulties for the same reason they have fits and learning difficulties. They are both due to a problem with the brain. If any of the special vision parts of the brain are damaged then visual difficulties are likely. This kind of visual impairment is known as Cerebral Visual Impairment (CVI).

What is Cerebral Visual Impairment?

Cerebral Visual Impairment (CVI) is a condition where some of the special ‘vision’ parts of the brain and its connections are damaged or not working. This causes visual impairment even though the eyes may be normal. Sometimes children with CVI actually have sharp vision but can not ‘make sense’ of what they see. In most cases, once damage to the brain has happened it does not get worse. As the child grows older the visual difficulties often improve.

How is the diagnosis made?

If a child is suspected to have visual impairment an assessment can be organised. Sometimes it is the parents who notice (by the way their child acts) that their child’s vision is impaired. If they discuss this with their Family Doctor an assessment can be arranged. Doctors, teachers and carers should always consider, that a child with West Syndrome is likely to have visual difficulties. If they suspect a child to have visual impairment an assessment should be organised.

CVI can be diagnosed in a child who has:

1. Visual Difficulty
2. Damage to the ‘vision’ parts of the brain
3. But apparently normal eyes

Often the best way to find out if a child has Cerebral Visual Impairment is by asking questions. A doctor can find out from the parents and teachers of the child what kind of problems they seem to be having. The questions are based on the visual difficulties that commonly occur in children with CVI. If the child has difficulties that are typical of the condition then they are very likely to have CVI.

What kind of visual difficulties is a child with CVI likely to have?

Most young children with Cerebral Visual Impairment feel their vision to be ‘normal’ as they have never known anything else but their own visual world. At first they assume that everyone else has vision the same as their own. They do not realise that other people see things differently. Because children may also have difficulty communicating they may not complain of visual difficulties.

Cerebral Visual Impairment can affect vision in many ways. All or only one of the special ‘vision’ parts of the brain can be damaged to different degrees. If there has been lots of damage to many parts of the brain the vision can be very poor. However the child may still see movement and bright lights. Complete blindness due to brain damage is rare.

If there has been only a small amount of damage in only one part of the brain the visual problem can be a lot less impairing.

Children with CVI can have problems with:

• Getting Around
• Recognising Objects
• Focusing for near objects
• Fast eye movements
• Visual Field Loss

The ‘dorsal stream’ helps children get around safely and quickly

The many different ‘vision’ parts of the brain combine together to make two visual ‘systems’.

One system helps the child to get around safely and quickly. It also helps the child pick objects up and avoid bumping into things and falling over. This visual system, that tells the body how to get around, is called the ‘dorsal stream’. It is called a ‘stream’ because it is a flow of information from one place in the brain to another, like water flowing in a stream. ‘Dorsal’ describes the part of the brain where the system is.

When the dorsal stream is damaged it is difficult to know precisely where things are in three dimensions. It can be difficult to:

• Use stairs without falling.
• Step onto pavements without tripping.
• Reach forward and grab a cup or handle.

Damage to the dorsal stream can also make it difficult to see a lot of different things at the same time. This means it can be difficult to find a toy on a patterned carpet or to see something that is pointed out in the distance amongst other things.

The ‘ventral stream’ helps a child recognise objects

The other system, called the ‘ventral stream’ helps us to recognise faces, objects and places. Damage to this system leads to problems:

• Recognising familiar faces.
• Knowing what common everyday objects are.
• Losing the way in places that should be well known to the child.

There are a number of other problems that can occur in children with CVI who still appear to have good vision. These include:

• Difficulty remembering things they have seen.
• Difficulty imagining ‘seeing’ things in their minds.
• Some children’s vision can become ‘tired’ more quickly than others. This means that their ability to see can vary from one time to another.
• Difficulty reading. This can be due to lots of different reasons.
• Vision may become worse when a child with CVI is trying to do something else at the same time. If they are listening hard, trying to speak or reaching out to hold an object their vision may become more blurred. If they are concentrating only on looking at an object, without trying to do anything else at the same time, vision is likely to become clearer and better understood.

Children with CVI can have difficulty focusing when looking at near objects

The focusing power of the eye needs to increase when looking at a close object. In children with CVI the focusing power can be reduced. It can also become tired more easily. This is the usual situation for most adults when they become 40 or 50 years old. When this happens many adults need reading glasses. Some children with CVI may also benefit from reading glasses for the same reason.

Children with CVI may have difficulty making fast eye movements

‘Fast’ eye movements are called saccades. We use saccade eye movements to quickly change the direction that our eyes are looking. This helps us:

• Look at something that has suddenly changed position
• Follow and fix accurately on a fast moving object
• Help us to move our eyes quickly across the page of a reading book

The eyes can then give clear signals to the brain to make clear vision. Saccades are important in many other visual tasks. Children with CVI may have difficulty making fast eye movements. These children may tend to make quick head turns when looking around a room or reading, rather than making fast eye movements. By using a few tips described in the ‘What can be done to help?’ section children with this difficulty may find reading a bit easier.

What is Visual Field Loss?

Visual field is the medical word for the full area that we can see: our visual world. If an area of our visual world is blurred or missing, with the rest clear, then visual field loss is present. It is due to damage to some of the special vision parts of the brain. The relationship between brain damage and visual field loss is all opposite to what you might think.

The right side of the brain is responsible for seeing the left side of the visual world. The left side of the brain sees the right side of the visual world. If the right side of the brain is damaged the left side of the visual world may not be seen. In the same way the upper part of the back of the brain is responsible for seeing the lower part of the visual world. A child with damage in this area will not see the ground when looking straight ahead. The child may then tend to trip over things.

What can be done to help?

There are no medicines or surgical treatments that will fix or improve brain damage. There are however lots of things that can be done to help children with CVI see better. We use our vision to get around, learn new things and to meet other people and make friends. It is important to consider what your child’s particular problems with vision might be now and in the future.

If your child has been prescribed spectacles, contact lenses or a Low Visual Aid (LVA) it is important that they are encouraged to wear and use them. This will help your child see more clearly and ensure the vision parts of the brain grow and develop.

Problems at school may be due to some of the reading books being hard to see. This often means it takes longer and more effort to do the work. If the size of print is increased and letters and words spaced more widely most children will find schoolwork easier. Good bright lighting and crisp black print on a clean white background will also make things easier. Sometimes placing reading books on a slope, which tilts the print towards the child, will improve reading speed as well. When reading it can be helpful to read one line at a time through a ‘letter box’ placed over the page. Placing a piece of blue tack below the line they are reading, at the beginning of the next sentence, can help some children find their way back to the start of the next line more quickly.

Some children may also benefit from using a computer programme while reading. The programme only shows one word of a sentence at a time. The word is in the middle of the computer screen. This reduces the need for fast eye movements.

It can increase reading speed and reduce tiredness. One programme is called ACE READER. There are many others. A demonstration can be downloaded from www.acereader.com. If you need any help with this please let us know.

It is also worth watching carefully to find out what the smallest toys are that a child can see and play with. Then try to only play with toys that are the same size or bigger. Placing one toy on a plain background will often help children see it more readily. Placing lots of toys of different size and colour close together on a patterned background can make them ‘invisible’ to many children with CVI.

Recognising facial expressions can often be difficult. It is worth trying to find out at what distance facial expressions can be seen and responded to. Then always try to talk and smile from within this distance. This helps a child to learn what facial expressions mean and to copy them. There is a special part of the brain that helps children ‘make sense’ of faces. Sometimes this part is also damaged. These children may have difficulty responding to smiling even if their vision is clear enough. If the child has visual field loss try to place objects in the part of the child’s vision that is working.

Cerebral Visual Impairment commonly occurs in children who have difficulty controlling both head and eye movements. Careful positioning of the head to prevent it falling to the side or falling forward can help a lot.

Infants and young children need to learn about the world around them. Home visiting teachers, physiotherapists and occupational and speech therapists may all add to the child’s care and education. It is important to continue the programmes that they recommend. If the child is involved in family activities vision can improve and new skills can develop.

There is also evidence that a customized intervention programme for children with visual impairment may help general development and improve vision. Some of the ideas that may help are outlined in the book ‘ Show me what my friends can see’ by P Sonksen and B Stiff. If you would like more information about this please ask us.

Even if a child has very poor vision many useful and practical things can be done to improve the ability of the child to get around, interact with other children and learn. See the Advice section on the VI Scotland Website.