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.
Marfan was the name of a French Paediatrician who first described this syndrome over 100 years ago. A syndrome is when a number of different conditions are seen together often enough that a pattern is recognised. The conditions can often affect quite different parts of the body. Children with Marfan's syndrome can have conditions that affect the heart, large blood vessels, lungs, bones, joints and eyes. Many children will be tall during childhood and reach over 6 feet in height in adulthood. Often one parent or brother or sister may also have this condition as well.
Marfan's Syndrome is caused by a misprint in a 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.
Often a child with Marfan's syndrome has been passed (inherited) a gene with a misprint in it from one parent (about 3 in 4 cases). 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 (about 1 in 4 cases). There is a 1 in 2 (50%) chance that the child of a person affected by Marfan's syndrome will inherit the condition.
The gene that is misprinted in Marfan's syndrome codes for a
protein called fibrillin. Fibrillin acts as 'glue and scaffolding'
for many parts of the body. It is especially important in the
heart, large blood vessels, lungs, bones, joints and eyes. Because
the code for this protein has a misprint it does not work properly.
This means that the bits of the body where it is important can
Children with Marfan's syndrome can develop conditions of the heart, large blood vessels, lungs, joints, bones and eyes
There are many conditions that can develop in children with
Marfan's syndrome. Some conditions need monitoring by a paediatric
doctor. The paediatric doctor can advise parents and children
on medicines and surgery that may sometimes be needed to help.
It is important to take advise on safe forms of exercise (low
intensity and non-contact) and antibiotic treatment during dental
operations to avoid complications of Marfan's syndrome. It is
not the aim of this information document to discuss all of these
other issues. The Marfan Association UK provide information sheets
on these other important aspects of Marfan's syndrome. Their
contact details are at the end of this document. The rest of
this document refers to how vision can be affected.
How does Marfan's syndrome affect the eyes?
The eyes of children with Marfan's syndrome can develop several different conditions. These include:
- Short-sightedness. This is also known as Myopia.
- A displaced lens. This is known as lens subluxation or dislocation if it falls out of place all together.
- Cataract. If the normally clear lens becomes hazy then cataract is said to be present.
- Retinal detachment. This is when the light sensitive film at the back of the eye peels off.
- Squint. This is when both eyes do not seem
to point in the same direction.
What is short-sight?
A child with short-sight can see better at short distance than long. This is also known as myopia. Children with myopia can see clearly when reading a book up close but may find 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 an eye is the more likely light from a distant object will focus short of the retina. Children with Marfan's syndrome grow big eyes. This is why they are short-sighted.
Light from a distant object can be focussed sharply on to the
back by wearing glasses. This will help a child with myopia see
clearly in the distance. Most children will then use the normal
near focussing power of the eye (accommodation) to see things
clearly for near through their corrective glasses.
The lens in children with Marfan's syndrome can often
Many children with Marfan's syndrome are born with a displaced lens in one or both eyes. It is usually displaced upwards. A displaced lens can cause:
- Double vision: This happens because light from an object can be 'split' into two by the displaced lens. This means two separate images are focused onto the retina. The eye will see double.
- Astigmatism: This is a condition where light from an object is not focussed to a single point on the retina. It is instead focused to several different points. The image of the object is 'smeared' across the retina. The object will be out of focus and blurred. This happens because the lens is not sitting in the correct position over the centre of the pupil but is instead tilted. Vision can usually be improved by wearing contact lenses or glasses.
- A completely dislodged lens: Sometimes the lens can become dislodged completely and fall into the back of the eye.
- Iritis: Iritis is when the iris in the eye becomes inflammed. 'itis' means 'to be inflammed'. -itis is often added to end of the name of a part of the body to describe an inflammatory condition of that part. Anti-inflammatory steroids help treat most cases of Iritis.
- Glaucoma: Eyes keep their shape by being
pumped up with water. It is a bit like a football being pumped
up and inflated with air. You can feel the 'pressure' in your
own eyes by gently feeling them through your closed eyelids.
The amount of pressure depends on the flow of water in and
out of the eye. If the flow of water out of the eye becomes
blocked the pressure goes up. This can happen if the lens becomes
displaced. High pressure in the eye can cause damage to the
optic nerve. Glaucoma is when the optic nerve is damaged by
high pressure in the eye. Drops or an operation usually help
to reduce the pressure.
Cataract is also more common in eyes affected by Marfan'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. During an operation the hazy lens can be removed and replaced with a clear plastic one.
Children with Marfan's syndrome can also develop retinal
Children with Marfan's syndrome have a higher chance of developing a retinal detachment. This is for two reasons:
- Short-sighted eyes are big. 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.
- Because of weak 'glue' (fibrillin) it even more likely that the stretched retina may tear and peel off.
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 Marfan's syndrome this may not work the first time and a second or third operation may have to be done.
If you wish more information on any of these conditions please
There is no single test that can be used. An eye doctor, usually along with a paediatric doctor can make a clinical diagnosis by examining all the parts of the body that might be affected. Often X-rays and an ultrasound picture of the heart (echocardiogram) are done.
For instance if myopia or a displaced lens is found in a young, tall child along with distinctive X-ray or ultrasound test results then Marfan’s Syndrome is more likely.
If there is also a history of one parent or 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.
Possibly in the future a genetic test for the misprinted fibrillin
gene may become available.
There are lots of things that can be done to help children with Marfan's syndrome 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.
Bright light often causes discomfort and reduced vision (photophobia). A sunhat and sunglasses may help reduce photophobia and glare. Special lenses that get darker in brighter light (photochromic lenses) are useful.
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
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 close together on a patterned background can make them difficult to see.
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. If the child has visual field loss try to place objects in the part of the child’s vision that is working.
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. We also suggest that you have a look at the other VI Scotland information documents for more information on some of the other eye conditions that can develop in Marfan's syndrome.