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Childhood Squint (Strabismus) information leaflet for parents and guardians

Patient information A-Z

Who is this leaflet for and what is its aim?

This leaflet provides information for parents and guardians about squints (strabismus) in children. It addresses the common questions about these, their possible effects on sight and treatment.

How do the eyes work together?

When the eyes work together as a pair they will be focusing at the same point when we look at an object. The brain will receive similar pictures from each eye so it can join them together to allow you to have binocular and three dimensional (3D) vision.

The movement of each eye is controlled by six muscles that move the eyeball in different directions. The muscles for one eye also coordinate with the muscles from the other one so that they can work together. The eyes also work together to take up a position, the position the eyes take in relation to each other can be described as the direction (or alignment) of the eyes.

What is a squint?

Squints (strabismus) are a group of eye conditions where the eyes are not looking in the same direction (not straight). When the eye turns inwards it is called a convergent squint (esotropia) and when it turns outwards it is called a divergent squint (exotropia). Less often, the eye may turn upwards or downwards (vertical squints).

Most commonly, only one eye turns and the other one looks straight but sometimes the turn changes from one eye to the other (alternating squint). The squint may be present all the time (constant squint) or only some of the time (intermittent squint).

The example below shows the right eye turning inwards (esotropia) and the left eye looking straight ahead. This condition is not always as obvious as shown here.

Example of the right eye turning inwards (esotropia) and the right eye looking straight ahead.

The picture below shows the left eye turning outwards (exotropia) and the right eye looking straight ahead.

Example of left eye turning outwards (exotropia) and right looking straight ahead

Squints are quite common and occur in approximately 1 in 20 children.

How are squints diagnosed (detected)?

Your child will have a full eye examination, including vision check, orthoptic assessment (examination of the eye movements and eye alignment) and examination of the eyes by a doctor or trained optometrist. The full eye check often includes the use of eye drops to dilate the pupils. The drops may sting when they are put in the eyes but this is short lasting. These drops have been used in children’s eye clinics for many years. After a full examination your child’s diagnosis and treatment options will be explained to you.

What are the causes of squint?

There are many different types and causes of squints. Your child’s eye specialist will explain to you the type and, where possible, the cause of your child’s squint after they have examined their eyes.

A squint can develop in early infancy or later in childhood.

Squints are sometimes caused by long sightedness and less commonly by short sightedness. Squints can run in families. Sometimes they may be caused by a problem with the nerve supply to the eye muscle (this is called a cranial nerve palsy or paresis) or by a problem in the eye itself.

However, in many cases the cause of a squint remains unknown.

How squints affect children’s vision

If a child has a squint they may develop reduced vision in the affected eye. This is called amblyopia (lazy eye).

A squint can reduce a child’s depth perception and 3D vision. This can make tasks like walking down stairs difficult. Older children (over 5 years old) may complain of double vision with a squint. This is when a child sees two images of the same object. They can sometimes adopt a change in their head position to reduce the double vision, which could involve tilting the head or turning the face to one side.

What is the treatment for a squint?

The treatment for a squint depends on its type and cause.

This often includes wearing glasses, patching or occlusion (explained below) and sometimes surgery, eye exercises or a combination of these treatments.

You will be asked to carry out patching (occlusion) if your child has amblyopia (lazy eye). The child has to wear an eye patch over the stronger eye for a few hours during the day to improve vision in the weaker (lazy) one. Patching should be used when the child is doing their usual activities (for example whilst in school).

More information about amblyopia can be found in our leaflet on this.

Your child’s eye specialist will explain in detail the treatment options for their squint.

In some cases no treatment is needed, but your child may be asked to attend regular check-ups in the eye clinic.

Can a child grow out of a squint?

A child does not usually grow out of a true squint. In adulthood, a person with a squint may be left with permanent amblyopia and problems performing tasks that require three dimensional (3D) vision such as pouring water into a cup or catching a ball when playing sports.

Sometimes very young children can appear to have a squint without there being a true misalignment of the eyes. This is usually due to the shape of the head and eyelids in very young children and is called a pseudo-squint. It does not require any treatment.

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Cambridge University Hospitals
NHS Foundation Trust
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Telephone +44 (0)1223 245151