University of Edinburgh
 

Medical Information on Retinoblastoma

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 be used as a means of diagnosing a condition.

We hope the information will help you to:

  • 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.

Medical Information on Retinoblastoma

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 Retinoblastoma?

Retinoblastoma is a very rare tumour of the retina. A tumour is a condition where a part of the body grows more than it would normally. This can cause damage in and around the eye, and to other parts of the body. Only about one child in very 20,000 is affected by this condition.

What is the cause of Retinoblastoma?

Retinoblastoma is caused by misprints in a child's genes. Genes are a book of chemical recipes read by the body to make things it needs. A child is given (inherits) a copy of all the genes from both parents. A child ends up having two copies of each gene, including the retinoblastoma gene. One copy comes from each parent. If a child has misprints in each copy of the retinoblastoma gene then they will develop a tumour of the retina (retinoblastoma). The medical word for a misprint is a mutation.

Why do misprints in genes develop?

Misprints occur by chance. Each gene is like a very long word that only uses four different letters. The order of the letters is crucial for the gene to be read and work correctly. A gene with a misprint will not work correctly. This often leads to disease. All the time, letters are accidentally changing and switching with each other, creating misprints. The body has a check and repair system that fixes any accidental misprints in the genes. Sometimes the check and repair system fails to correct a misprint. The letter might not be replaced at all or replaced by a different one.

If misprints occur to both copies of the retinoblastoma gene then the child will develop a tumour of the retina (retinoblastoma). These children are most likely to develop retinoblastoma in only one eye. Children like this often present to eye doctors in their third year of life.

A child can be born with one copy of the retinoblastoma gene already misprinted

If a child has a family history of retinoblastoma (such as a parent with the condition) or develops a misprinted gene while in the womb then they are more likely to also develop a tumour of the retina. This is because they are more likely to have inherited and end up being born with one copy already misprinted. This is called a ?germline? mutation. Now these children only need a single further misprint in the other copy of the gene to develop a retinoblastoma. These children are most likely to develop a retinoblastoma in their second year of life, or even earlier (sometimes at birth). They are also more likely to develop retinoblastoma in both eyes rather than in only one eye. If an eye is affected these children are more likely to develop several tumours rather than just one. Occasionally (about one child in every 50 to 100) a rare type of brain tumour called a trilateral retinoblastoma is also found in children with heritable retinoblastoma or a germline mutation. These children are also more likely to develop tumours of other parts of the body when they get older. When these children grow up and become parents they are also more likely to pass a misprinted retinoblastoma gene on to their own children. This type of retinoblastoma is known as 'heritable'.

Children with 'Heritable' Retinoblastoma can develop other types of tumours

Children with 'heritable' retinoblastoma are at risk of developing other kinds of tumour. Bone tumours are the most common kind. They usually only develop in adulthood. There is about a 1 in 10 chance that this might happen.

Some children are born with no misprints but still develop Retinoblastoma

These children develop misprints in both copies of their retinoblastoma gene after they are born. Because two chance events must occur, these children are more likely to present later, often in their third and fourth years of life. Usually only one eye is affected. When they grow up they are unlikely to pass on a misprinted retinoblastoma gene to their children. They are not usually at risk of developing other types of tumours.

This is only a brief summary of the genetics of retinoblastoma. There are exceptions to these general rules. This is why it is important that families with a child affected by retinoblastoma receive counselling from a specialist in genetics.

How does Retinoblastoma present?

There are four main ways that a retinoblastoma can present. These are:

  • A white pupil (leucocoria)
  • Squint (when both eyes don't appear to point in the same direction)
  • Red eye
  • Blurred Vision

The most common way is when the normally black pupil in a child's eye looks paler or white. Parents may notice this in photographs of the child. The medical word for white pupil is Leucocoria. Leuco means white. Coria means pupil.

Retinoblastoma may also cause a squint, red eye and blurred vision. Both parents and child might notice this. Parents should discuss any concerns with their family doctor. An assessment by an optometrist or ophthalmologist can then be organised.

How is Retinoblastoma diagnosed?

If an eye doctor suspects during an examination, that a child might have a retinoblastoma then other tests are usually needed.

In young children it is easier to do a thorough examination of the eye while they are asleep under a General Anaesthetic. While a child is asleep it is also easier to perform scans of the eye and brain. Other tests may also be done at the same time. These might include taking samples of the child's blood, bone marrow and water that surrounds the brain. These tests all help to confirm the diagnosis of retinoblastoma. They also help to make sure the retinoblastoma has not spread to other parts of the body. These tests provide all the information that is needed to decide how best to treat the condition.

How is Retinoblastoma treated?

Any treatment that is recommended is fully discussed with the parents and child. Different hospitals may recommend different ways to treat retinoblastoma. It will depend on the previous experience and opinion of the doctors. The way retinoblastoma is treated is always changing as new ideas and new methods are used. This information document describes a consensus of current opinion.

Treatment depends on how large the tumour is, if it is affecting one eye or two and whether any spread has been found. If the retinoblastoma is medium or large sized and in only one eye then removal of the eye is usually recommended. This is called enucleation. Within a few weeks an artificial eye (prosthesis) can be fitted. If retinoblastoma is found in both eyes then it is recommended that the worse eye (if it is a large tumour) is removed. The other eye is treated differently. The aim of treatment to the other eye is to shrink and kill the tumour but otherwise leave the eye as normal as possible. By doing this it is hoped that some useful vision can be left for the child. This is known as 'conservative' treatment.

There are different ways of treating conservatively

There are a few different methods used for treating retinoblastoma conservatively. They may be used alone or together depending on the features of the tumour. These include:

  • Injecting medicine into veins (chemotherapy)
  • Focal laser treatment or cold treatment (cryotherapy) directly to the eye
  • X-Ray treatment (beam radiotherapy or local plaques)
  • Surgically removing the tumour

Laser treatment is best at treating small tumours while cryotherapy is better at treating medium sized tumours. Chemotherapy is often used first to shrink tumours before applying focal laser or cryotherapy.

Different treatments have different success rates and different side effects. Some treatments take several weeks to complete and need lots of trips to the hospital.

Some radiotherapy treatments increase the risk of developing a hazy lens in the eye (cataract) or even new tumours. However in general the risk of receiving treatment is less than the risk of not having treatment. Any treatment that is recommended is fully discussed with the parents and child.

Why is conservative treatment not done in every case of Retinoblastoma?

With conservative treatment there is a small risk that the retinoblastoma will grow again or even spread to other parts of the body. This is because a small amount of tumour may remain and grow again. There is very little chance of this happening if the whole eye and the entire tumour is removed by an operation (enucleation).

What else needs to be done after the initial treatment?

Usually the child will be seen every 3 to 6 months in the eye clinic. This is to make sure that no new tumours are growing. It is also important that the family gets a chance to meet a geneticist. This is to discuss the risks of future children and grandchildren developing retinoblastoma.

How does Retinoblastoma affect the way a child sees?

Most children with retinoblastoma in only one eye usually have good vision in the other. These children do not normally complain of reduced vision. When both eyes are affected the child is much more likely to have blurred vision.

Usually when a child presents the vision in the affected eye is very poor. This is because the tumour is usually covering the pupil blocking vision. If the eye is removed (enucleated) there is no means that any vision can be regained on that side.

If the tumour is treated conservatively then usually some vision remains. The level of visual impairment will depend on the size of the tumour and where it is at the back of the eye. If the tumour is small and placed away from the center of the retina then vision may remain good. If the tumour is large and growing from the central part of the retina then vision is likely to be poorer Most children with retinoblastoma maintain good vision. Sadly a small number can develop significant sight loss.

What can be done to help children with sight loss?

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 symptoms of photophobia. Special lenses that get darker in brighter light (photochromic lenses) are also known to be 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. 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 sometimes make them even more 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.

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 one to improve the ability of the child to get around, interact with other children and learn.

For further advice and support contacting other parents with children who have retinoblastoma can help. Organisations such as LOOK, RNIB and VI Scotland can put parents in contact with each other. There are also a few retinoblastoma support groups that can be contacted via the Internet.

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 worked as an Ophthalmology Research Fellow with Visual Impairment Scotland and is a member of the Royal College of Ophthalmologists.

vis logo