Visually Impairing Conditions
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 and should not to be used as a means of diagnosing a condition. It is not a means to access a 'second opinion' particularly in any medico-legal cases. 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
Due to staffing limitations we are not able to offer telephone or email advice to parents of children who are not notified with VI Scotland.
These pages represent the consensus of opinion of many different people who 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.
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
What we see is made in the brain from signals given to it by
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 focusing 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.
If damage occurs to the retina or optic nerve then some of the wires wear out and disappear. This is known as optic atrophy. By looking into the eye with a special instrument all these wires can be seen 'end on' as they exit the eye and pass to the brain. This is the 'head' of the optic nerve. If none of the wires are damaged then the head of the optic nerve looks yellow and pink. If many wires are missing then the optic nerve looks pale and white. This is the common appearance in children with optic atrophy.
There are many different causes of optic atrophy. Often no cause can be identified and the condition is unexplained. This is often called 'idiopathic'. Recognised causes of optic atrophy include:
- Problems during pregnancy, labour and the early days of a baby's life that result in poor oxygen and blood supply to the baby can lead to optic atrophy
- Infection of a child's brain (meningitis) can sometimes cause optic atrophy
- Some specific optic atrophy conditions are known to run in families
- Other optic atrophy conditions can occur for the first time in a family as a result of marrying a cousin or a more distant relative
- Occasionally some diseases of the baby's metabolism can cause optic atrophy
- Some drugs if taken during pregnancy are associated with the development of optic atrophy
- If pressure is applied to an optic nerve by a growing mass
then optic atrophy can occur.
Most young children will 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 and do not realise that other people see things differently. Depending on the cause of the optic atrophy the vision can sometimes improve as the child gets older or with treatment of the cause.
Optic atrophy can affect vision in different ways. If only a small number of wires in only one optic nerve have been damaged and the optic nerve is almost normal then the child may also have normal vision. If both optic nerves have lost most of the wires then the child will have reduced sharpness of vision and may only see bright lights and large shapes. Optic atrophy often initially causes problems with central vision and colour vision.
Sometimes children with optic atrophy can develop fast 'to-and-fro' movements of the eyes (nystagmus). A squint can also develop.
Wearing spectacles can often improve vision. If the vision is worse in one eye than the other sometimes patching the better eye will help to improve the vision in the other. Special low visual aids may also be provided. These can all improve the child's vision.
How can parents, family, friends and teachers make a
There are lots of things that can be done to help children with optic atrophy make the most of their vision.
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
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.
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 difficult to see for many children with impaired vision.
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.
A child who chooses to use a head turn or to move the head to and fro to improve vision should not be made to stop doing this. They are trying to improve their vision and are often doing it without knowing it.
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.
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.