University of Edinburgh
 

Visually Impairing Conditions

by Dr Andrew Blaikie for VI Scotland

Medical Information on Microphthalmia

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 be used as a means of diagnosing a condition.

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

Authors

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. If you have any questions or comments regarding the information please contact:

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

Email : viscotland@ed.ac.uk
Website : www.viscotland.org.uk

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Medical Information on Microphthalmia

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 Microphthalmia?

When a baby is growing in the womb sometimes not all the parts of the baby grow fully. If an eye (ophthalmia) does not grow to its full size and is smaller (micro) than it should be this is known as Microphthalmia. If the eye does not grow at all then this is known as Anophthalmia.

What is the cause of Microphthalmia?

Most cases of microphthalmia occur by chance although some cases are known to run in families. Very rarely an infection in the womb can lead to microphthalmia. It can often be seen along with other eye conditions. There is no good evidence that microphthalmia is caused by prescription or recreational drugs.

How is Microphthalmia diagnosed?

Microphthalmia can be diagnosed in the eye clinic during an examination by an ophthalmologist. The eye can be measured. This is often done using an ultrasound scan. If it is smaller than normal then microphthalmia is diagnosed.

How does Microphthalmia affect a child's vision?

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. They do not realise that other people see things differently.

Microphthalmia can affect vision in different ways. If the eye is only slightly smaller than the normal then the child may have normal vision. If both eyes have almost completely failed to grow properly then the child may be more severely visually impaired. They may only see bright lights and large shapes.

Children with milder forms of microphthalmia tend to be long sighted (hypermetropia). They may benefit from wearing glasses.

Sometimes children can develop fast to-and-fro movements of the eyes (nystagmus). Squint can also develop.

If you would like VI Scotland documents on any of these conditions please ask us.

Are their any conditions associated with Microphthalmia?

Sometimes, as well as the eye being smaller than normal, other parts of the eye do not grow correctly. This can lead to problems with:

  • Raised pressure in the eye (glaucoma)
  • A cloudy lens (cataract) and
  • Poor vision because the retina is not working properly

If you would like VI Scotland documents on any of these conditions please ask us.

Occasionally when the baby is in the womb parts of the face and mouth do not grow correctly. The most common problem is cleft palate where the nose or lips do not form properly.

Microphthalmia can sometimes also be associated with learning difficulties.

How can doctors help?

Patching of the child's better eye can encourage the poorer eye to develop better vision. Sometimes children with microphthalmia need glasses to see more clearly. This is because the may be long-sighted. Contact lenses or glasses can be worn to improve the appearance of a small eye.

Growth abnormalities of the face and lips such as cleft palate can be corrected by operations.

If other problems develop, such as cataract or glaucoma, an ophthalmologist can offer treatment to help. This may be by using drops or performing operations.

How can parents, family, friends and teachers make a difference?

Many things can be done to help children with Microphthalmia see better.

We use our vision to get around, learn new things and to meet other people and make friends.

Most children with Microphthalmia give the impression that their vision is normal. It is important however to consider what your child's particular problems with vision might be.

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 correctly. Wearing a hat and tinted glasses can also help reduce problems from bright light. 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 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.

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 'invisible' to some children.

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