(Strabismus) in children
A squint occurs when the eyes do not look in the same direction.
Usually when one eye is looking straight ahead the other eye
is pointing inwards, outwards, up or down.
Most squints occur in young children and problems arise firstly
if the child stops using the affected eye to see with and
secondly if the appearance of the squint causes the child
If the child stops using the affected eye to see with, this
can lead to visual loss called amblyopia which can become
permanent unless treated in childhood. Amblyopia is usually
treated by patching the good eye to force the affected eye
If the appearance of the squint is unacceptable, surgery may
be required to try and realign the eyes.
causes a squint?
problems can be caused by a squint in a child?
do you know if your child has a squint?
How are squints
for squint in children
What causes a squint?
The movement of each eye is controlled by six different muscles
that pull the eyes in various directions.
A squint develops when the eye muscles do not work in a balanced
way and the eyes do not move correctly together.
Approximately 1 in 20 children over the age of 20 months have
There are a number of reasons why children develop squint:
Congenital squints of unknown cause
Congenital means that the child is born with a squint, or
it develops within 6 months of age. In the majority of cases
the exact cause is unknown and in most cases one eye turns
inward. This is called a Congenital Esotropia (or an infantile
This is a common type of squint and tends to run in families,
although not always.
In some cases the eye may turn outwards in which case it is
called a Congenital Exotropia.
Squint related to refractive errors
Refractive errors include short sight (myopia), long sight
(hypermetropia) and astigmatism. When a child has a refractive
error and they try to focus clearly, one of the eyes may turn
in the wrong direction and they can sometimes develop a squint.
This type of squint tends to develop in children over the
age of two years, particularly in children who are long sighted.
The squint most commonly involves one eye turning in (an esotropia).
Wearing glasses to correct the long sight will often correct
The majority of children who develop a squint are otherwise
healthy and have one of the above types of squint.
In some cases children may have a squint as part of another
medical condition, commonly a genetic or brain condition,
for example children with cerebral palsy, hydrocephalus or
an injury to the brain.
What problems can be caused by a
squint in a child?
Ambylopia is sometimes called a ‘lazy eye’. It
is a condition in which the vision in an eye is poor because
of lack of use of the eye early in childhood.
The visual loss of ambylopia is permanent if not treated before
the age of about seven years and after that cannot be corrected
with the use of glasses.
In order to understand ambylopia it is helpful to understand
how vision normally develops.
When a baby is born, although it can see, its visual system
is not fully developed. The visual system (eyes and parts
of the brain that interpret vision) continues to develop and
mature until the age of about 7 years. In order to mature
properly, the brain needs signals from the eyes about what
they can see. If for any reason a young child does not use
one or both of its eyes properly, then vision will not be
learnt properly and it will develop poor vision, ambylopia.
Essentially, ambylopia is a developmental problem of the brain
and visual pathways, rather than the eye itself.
A squint is a common cause of ambylopia because the brain
ignores the signals from the eye that turns in the wrong direction.
As a result of this the visual system related to this eye
fails to develop properly and it becomes an amblyopic eye
with poor vision.
There are also other causes of ambylopia.
The cosmetic appearance of the squint
A squint can be a cosmetic problem as often people may notice
the eye ‘wandering’. It is possible to correct
a squint by operating on the muscles around the eye to try
and realign them so that they work more effectively together
and the eye does not ‘wander’.
Impaired depth perception
In eyes that work normally together, both eyes look and focus
on the same spot, this is called binocular vision. The brain
is able to combine the images seen from each eye to form a
three-dimensional image and gives us the ability to perceive
If a child has a squint, and the eyes do not point in the
same direction, the brain learns to ignore the image from
the squinting eye so that the child does not notice double
vision from seeing two images. However if the eyes are not
looking at the same point, then the child will not develop
binocular vision and will not have a good sense of depth when
looking at objects.
As adults they may not notice much problem from this as they
will adapt, but some jobs do require good depth perception
and they may be excluded from a small number of professions,
those usually involving work with a microscope and very fine
vision such as airline pilots. Eye doctors also require very
How do you know if your child has
Firstly all newborn infants should have their eyes checked
at birth and at a 6 to 8 week review to look for any evidence
of a squint or other eye problems.
It is essential that all children have a pre-school eye check
aged 4-5 years to check their vision and specifically look
for a squint.
Obviously if your think your child has a squint you should
take them to see an Ophthalmologist for a review.
How are squints treated?
Squints are treated with a combination of the following measures:
• If the child has a refractive error (is long or short
sighted) they will usually be given glasses to try and improve
• If they appear to have some visual loss (ambylopia)
in one eye, then the doctor will try to treat this, usually
by getting the child to use a patch over the good eye for
some hours every day to encourage the ‘lazy eye’
to work harder and improve the vision (a process known as
• Surgery may be required to improve the appearance
of the squint and in some cases may help the eyes work together
and give some binocular vision.
Surgery for squint in children
In many cases an operation is needed to try and improve the
cosmetic appearance of the eyes. Sometimes surgery can help
give some degree of binocular vision, although this is often
The exact nature of the surgery depends on the type of squint,
but in general it involves altering the position of one or
more muscles where they attach onto the eye.
Squint surgery will usually reduce the amount of squint although
sometimes more than one surgery may be needed. Sometimes even
after successful surgery the squint can return years later
and further surgery can be considered.
The surgery needs to be performed under general anaesthetic.