Medical information on Axenfeld-Rieger Syndrome
by Dr Andrew Blaikie for VI Scotland
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.
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.
We hope the information will help you:
- 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.
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. All parts of the brain and eye need to be present and working for us to see normally.
A syndrome is when a few different conditions are always seen together. The conditions can often affect quite different parts of the body. Axenfeld-Rieger Syndrome is when a child has congenital glaucoma but also a typical flattened appearance to the nose and face with fewer teeth than normal. Very rarely the child may also have poor hearing, learning difficulties and problems with the heart. The condition is named after the doctors who first described it.
What is Congenital Glaucoma?
A congenital condition is one that a child is born with. Glaucoma is when the optic nerve is damaged by high pressure in the eye.
What causes high pressure?
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. Water drains out of the eye through a narrow gap between the coloured part of the eye (iris) and the clear curved window at the front (cornea). Eye doctors often call the drainage gap the 'drainage angle' or 'trabecular meshwork'. Some children are born with a blocked drainage angle. This leads to high pressure in the eye. High pressure in the eye can cause damage to the optic nerve.
Why are some children born with a blocked drainage angle?
Most cases occur by chance. Axenfeld-Rieger Syndrome can occur more commonly in some families. If a parent has the condition there is a risk of other children being born with the same condition.
Occasionally children with unaffected parents who are cousins or more distant relatives may be born with congenital glaucoma.
This is only a brief summary of the genetics of Axenfeld-Rieger Syndrome. Any family with a history of this condition should seek counseling from a specialist in genetics.
Children with Glaucoma sometimes do not like bright light or going outdoors. This is called photophobia. The child's eyes may also water constantly. Sometimes parents notice their child's eyes to be larger than other children. If the pressure in the eyes is very high the cornea may look hazy and not as clear as usual. If parents notice these signs they can ask their Family Doctor to arrange an examination by an Eye Doctor.
The damage to the optic nerve from the high pressure does not initially cause any problems with vision. If though the high pressure is not treated the optic nerve damage can become worse. The child may slowly develop haziness of vision that creeps in from the edges to cause blurred central vision.
High pressure in an eye of a child can also make the eye grow bigger than usual. This is called 'buphthalmos'. Children with bigger eyes usually become short-sighted. This is also known as Myopia. These children will need spectacles to see clearly in the distance. Children with buphthalmos are also more likely to develop a squint or lazy eye.
Sometimes the cornea can be hazy. This is most often seen when the pressure is high. If the pressure is lowered then the cornea usually becomes clear again. After the cornea clears small 'cracks' on the inside surface of the cornea might still be seen. They are called Haab's Striae. They do not usually affect vision.
Axenfeld-Rieger Syndrome can be diagnosed during an eye examination. The eye doctor looks for typical features. The most important signs include:
- checking the pressure in the eye
- examining the drainage angle
- looking at the optic nerve.
If the pressure is high then Glaucoma is likely. Sometimes using a small mirror it is possible to look at the drainage angle. Water in the eye drains out at the drainage angle. In Glaucoma it can often look different from usual. If the angle looks blocked or not fully developed then this might explain why the pressure is high. The way the optic nerve looks can also help to make a diagnosis. In Glaucoma damage occurs to the optic nerve. This causes some of the wires within it to wear out and disappear. 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 Glaucoma. Eye doctors often describe the damage to the optic nerve head as 'optic disc cupping'.
Younger children can be difficult to examine when awake. It is easier while they are asleep, under a short anaesthetic. While asleep the eye doctor can check the pressure in the eye and the appearance of the head of the optic nerve. Most young children will need short anaesthetics once or twice a year to do this.
Axenfeld-Rieger Syndrome is diagnosed if glaucoma is confirmed along with other signs such as a flattened appearance to the nose and face and fewer teeth than normal.
If the pressure in the eye is lowered the damage to the optic nerve usually stops. The pressure can be lowered by several different kinds of operation. All the operations work by trying to increase the flow of water out of the eye. This usually helps to lower the pressure and prevent further damage to the optic nerve.
If a skin is blocking the drainage gap of the eye it can be cut open. This is called a Goniotomy. This allows more water to drain out of the eye and lowers the pressure. If this does not work other kinds of operations can be done (e.g. Trabeculectomy or Drainage Tube Insertion). Sometimes drops can also be given to help lower the pressure.
Axenfeld-Rieger Syndrome can occur more commonly in some families. All other family members should be examined for evidence of Glaucoma. If other members have Glaucoma they will also need treated.
How can parents, family, friends and teachers make a difference?
We use our vision to get around, learn new things and to meet other people and socialise. Most children with Glaucoma have few problems getting around. Their behaviour can therefore give the impression that their vision is normal. It is important however to recognise their particular limitations of vision.
If your child has been prescribed spectacles or a Low Visual Aid (LVA) it is important that they are encouraged to use them. This will help your child see more clearly and ensure the vision parts of the brain grow and develop correctly. Wearing a hat and tinted glasses can also help reduce discomfort from bright sunlight. If your child has been prescribed drops they should be used regularly as advised by the nurses and doctors at the eye clinic.
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 most children will find schoolwork easier, especially if they also use their LVA. If a child has been given an (LVA) then they should be encouraged to use it.
It is 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.
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.
Even if a child has very poor vision many useful and practical things can be done to help.
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 was an Ophthalmology Research Fellow with Visual Impairment Scotland and is a member of the Royal College of Ophthalmologists.