INSIGHT INTO SQUINT

by Moorfields Eye Hospital

What is a squint?

It is the common name for 'strabismus' which is the medical term used to describe eyes that are not pointing in the same direction. You may have heard it called 'lazy eye' or 'cast' according to the direction of the turn of the eye.

Medical term	Definition of term	Common term
Esotropia (convergent squint)	Eye turned in	Cross-eyed Boss-eyed
Exotropia (divergent squint)	Eye turned out	Wall eyes
Hypertropia (vertical)	Eye turned up
Hypotropia (vertical)	Eye turned down

The squint may be present all or only part of the time, in only one eye or alternating between the two eyes.

Why do squints develop?

There are a number of reasons. The main ones are:

• Refractive (focusing) abnormality
• Eye muscle imbalance

These separately or together cause squint.

• It can run in families
• Illness - can make it obvious
• Injury
• Rarely, it can be due to other diseases or illness.

Some babies may appear to have a squint that is not a true squint. It is called 'epicanthus' and is caused by folds of skin on a wide nose. Epicanthus does not exclude the possibility of a squint being present and so you should always seek an expert opinion.

Treatment
How will the squint be managed?

• By one or more of:
• Refraction (test for spectacles) and wearing spectacles.
• Patching
• Operation

Refractive Abnormality and Spectacles

The main refractive (focusing) error to be the cause or part of the cause of convergent squint is: Hypermetropia (long sight).

	No refractive error: light rays fall on the retina.
	Hypermetropia (long sight). Light rays fall beyond the retina.
	Long sight corrected with spectacle lens. Light rays fall on the retina.

Will my child need to wear glasses?

This is decided by the ophthalmologist (the eye surgeon responsible for the management of your child's squint) after refraction.

Refraction involves your child first having some drops or ointment to both eyes to dilate the pupils (make them bigger).

Then the optometrist measures what lens is needed by shining a special light into the eye and seeing how its reflection is changed. Appropriate lenses are put into a (trial) frame and older children read the test chart.

Do the glasses have to be worn all the time?

Yes unless advised otherwise.

How do we obtain the glasses?

All children are entitled to a grant (voucher system) towards the cost of new glasses. In the Visual Assessment Department we specialise in children's care and hold a good selection of frames at competitive prices. We ensure you are able to have a pair of glasses without additional payment. However, you may choose a more expensive frame and prefer to pay the difference. Spectacles can usually be made in about 1-2 hours whilst you wait.

If you choose to take your prescription to an optician in an outside practice, Moorfields cannot take responsibility for how these are made or for repairs or replacements.

Can we have a spare pair of glasses?

Yes, but you must pay the full cost yourself.

What do we do if the glasses break?

These days all children have glasses with plastic lenses. These are lighter in weight and less likely to break. Moorfields will repair the glasses when necessary and allow a voucher towards the repair.

Eye Muscle Imbalance and Occlusion (Patching) In order to focus both eyes on an object all the eye muscles of each eye must be balanced and work together. When one eye turns that eye is not focused properly and the vision can deteriorate in the squinting eye.

An orthoptist carries out a series of eye tests to determine the presence of a squint. In some children who develop a squint patching the good eye will make the lazy eye work harder and, therefore, the vision improves.

How does a patch affect the squint?

Patching purely improves vision. The unpatched eye will appear to be straight while the patch is worn. Sometimes when the patch is removed the squint may be temporarily more noticeable but later returns to the pre-patching position.

Will my child need to wear a patch?

Possibly if your child is less than about 8 years and if the vision in one eye is reduced because of the squint. This will mean regular visits to the Orthoptic Department.

Which eye does the patch need to be put on?

On the straight eye so that the eye with the poorer vision is used on its own for some part every day. It is a very effective way of improving vision.

Does my child wear his glasses and the patch?

Yes, the patch should be worn on the face. It is made from non-irritating material to prevent rashes. Spectacles are worn over the patch.

How long should the patch be worn?

This varies according to the child's need and may be from less than 1 hour a day to all day. Close work activities such as colouring, reading or schoolwork should be undertaken during patching. It can be useful to negotiate this with your child's teacher(s).

It is important that the child is involved in some near vision activity during patching. This will achieve maximum effect and help the child comply with patching because it distracts attention from the patch. Perseverance with patching is vital.

Can exercises cure the squint?

They can help to control some intermittent squints in older children.

Operation
Will an operation help?

Many children with squints do need an operation in addition to glasses or patching. The operation is confined entirely to the surface of the eye. The muscles which are attached to the outside of the eye are moved to a new position on the surface of the eye. Usually the muscles of the squinting eye are operated upon, but sometimes it may be necessary to operate on the muscles of the other eye as well, as this often gives better results. Often one operation is effective but some will need further operations. Even an operation cannot ensure perfect alignment afterwards. In any squint surgery the focusing parts of the eye are never operated on and there is no significant risk of your child's sight being damaged by the operation. For any eye operation the eye is NEVER brought onto the cheek for surgery.

Can you tell us about the hospital stay?

It is normally suggested by the Children's Patient Care Co-ordinator in the Outpatient Department, that you visit the Children's Ward before the hospital admission. She will give you an information leaflet and poster. The day of admission your child will be seen by the orthoptist, the ophthalmologists and the anaesthetist (the doctor who puts your child to sleep for the operation).

Before going to the operating theatre, your child will be given some syrup/tablet to make him sleepy. One parent is allowed into the anaesthetic room until the child is fully asleep. If the child stays overnight, one parent is allowed to stay on the ward with their child.

Before returning home, the nurse will clean around the child's eye and instil drops. The doctor will see your child and ensure he is fit for discharge. An appointment will be made for 10-14 days after this. Usually drops will need to be used at home. The nursing staff will show you how to instil drops.

General Questions
Is squint common?

About 2% to 3% of the population have a squint.

Is my child too young to start treatment?

No, the earlier the better.

Does it matter if the squint is not treated?

Yes:

• Your child will NOT grow out of the squint
• Sight will get worse in the affected eye
• He may be teased about his appearance
• He may be precluded from some jobs later
• If at some later point the sight in the better eye is lost e.g. by accident, the squinting eye could not compensate and your child would be visually handicapped.

Should other children be checked for squint?

Yes, because squint can run in families.

What other services are available?

The Sick Children's Trust 'Home from Home'
Accommodation for relatives to support their child throughout the hospital stay. Contact the House Manager: 020-7251 6009 Mon.-Fri 9-4. or ward staff.

Social workers
Provide advice and support for parents of a child with a visual problem. Contact Social Work Department 020-7253 3411 during office hours.

Paediatrician
A doctor who specialises in children's conditions is available in the Children's Ward on Tuesday and Thursday and can give advice on developmental and educational matters.

Principal, Family Support Services
Provides support for the family and child, usually with a more chronic condition and developmental/educational implications with the offer of home or school visiting.