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?
- Parents' Support Group
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 the parts of the brain and eye need to be present and working for us to see normally.
This is a condition that mainly affects the eyes. Most children will however also have a distinctive facial appearance. Often one parent or a brother or sister may also have this condition. Children with this condition are usually very short-sighted from an early age. This is the most common affect of this condition upon the eyes. Children with Stickler's syndrome are also more likely to develop Retinal Detachment and Cataracts.
Stickler's syndrome is caused by a misprint in the child's genes. Genes are a book of chemical recipes read by the body to make things. A misprint in a recipe may cause a part of the body not to work correctly. Sometimes many parts of the body do not work correctly. A child with Stickler's syndrome has often been passed (inherited) a gene with a misprint in it from one parent. This is called Autosomal Dominant Inheritance. Sometimes by chance a new misprint may occur in the child’s genes and the parent's genes are normal. There is a 1 in 2 (50%) chance that the child of a parent with Stickler's syndrome will inherit the condition.
Short-sight is also known as Myopia
A child with Myopia can see better at short distance than long. Often children with myopia can see clearly when reading a book up close but often find the television or the blackboard at school blurred.
A short-sighted (or myopic) eye cannot focus the light from an object at long distance sharply onto the retina at the back of the eye. Instead the light focuses to a sharp point in front of the retina. The vision is then blurred. If the object is brought nearer the eye, the point at which the light focuses sharply will move backwards onto the retina. An object at a short distance then becomes clear: the eye is short-sighted.
The bigger and longer and eye is the more likely light from a distant object will focus short of the retina. Children with Stickler's syndrome grow big eyes. This is why they are short-sighted.
Children with Stickler's syndrome can also develop retinal
Children with Stickler's syndrome have a higher chance of developing a retinal detachment. This is because eyes that are short-sighted are bigger. Although the outer covering of the eye is bigger the retina inside is not. The retina has to 'stretch' to cover the whole of the back of the eye. Sometimes a tear or a hole can appear in the stretched retina. If this occurs water from within the eye can leak down behind the retina. As the water seeps in it causes the retina to come away (detach) from the back of the eye. A retinal detachment will then be present.
Cataracts are also more common in eyes affected by stickler's
Cataract is when the normally clear lens of the eye becomes hazy. If the lens is not clear then not all the light can get into the eye and vision is often blurred. Although the cataract may be present in childhood it does not normally cause blurred vision until adulthood.
An eye doctor can diagnose this condition during an examination. If Myopia is found in a young child along with the distinctive facial appearance then Stickler's syndrome is more likely. If there is also a history of one parent or a brother or sister having the condition then it is almost certain the child is also affected. As the child grows older a special type of cataract may also be seen. Due to its shape this is sometimes also called a 'wedge' or 'fleck' cataract.
How is Myopia diagnosed?
Sometimes parents and teachers notice, by the way a child acts, that their vision might be impaired. Children may have difficulty seeing the blackboard at school and hold books very close to read. They may narrow their eyelids and half close their eyes when looking at things in the distance. If parents discuss this with their Family Doctor an assessment can be arranged.
An eye doctor or optometrist can diagnose myopia during an examination. The level of Myopia can be assessed by shining a light, through different lenses, into the eye of the child.
The level of myopia is measured in focussing power units called dioptres. Minus units are used to describe myopia. Mild myopia is between zero and minus five dioptres. Moderate myopia is between minus five and ten dioptres. Severe or 'high' myopia is greater than minus ten dioptres. Most children with Stickler's syndrome have high myopia. The level of Myopia tends to be stable and does not usually increase after the age of five years.
Spectacles or contact lenses can usually sharpen vision. Sometimes
the vision will not be perfect. This can be because of other
problems with the eye, such as cataract or retinal detachment.
How is Retinal Detachment treated?
If the retina detaches then an operation may help. A surgeon would try to drain the water from underneath the retina, close the hole and then 'stick' the retina back down on to the back of the eye. This can often help fix the problem. Often in Stickler's syndrome this may not work the first time and a second or third operation may have to be done.
How can parents, family, friends and teachers make a
We use our vision to get around, learn new things and to meet other people and make friends.
It is important that children are encouraged to wear their spectacles or Low visual Aids (LVAs). This will help the child see more clearly. It will also help the vision parts of the brain to grow and develop correctly.
Even if a child has very poor vision many useful and practical things can be done to help.