Abnormal alignment of the gaze of one of the eyes, also known as crossed eyes or squint

  • Often occurs in early childhood
  • Sometimes runs in families
  • Gender and lifestyle are not significant factors

Strabismus is a common condition in which only one eye points directly at the object being viewed. This abnormal alignment of the eyes causes the brain to receive conflicting images, which may result in double vision or, in children under the age of 8, suppression of the image from the misaligned eye.

Strabismus can be caused by any disorder of vision, such as longsightedness (see Hypermetropia) or shortsightedness (see Myopia), and can run in families, suggesting a genetic factor. The condition may be caused by a structural difference in the muscles that control movement of the eyes. Very rarely, strabismus develops as a result of cancer of the eye (see Retinoblastoma) or paralysis of the muscles in one eye caused by a serious underlying condition such as a tumour in the brain (see Brain and spinal cord tumours in children).

Most babies squint occasionally up to the age of about 3 months, and this is normal. However, a squint after the age of about 3 months or a persistent squint at any age is abnormal and parents should consult their doctor.

What are the symptoms?

If the condition is mild, the symptoms occur only when a child is tired, but in severe cases, they are present all the time. The symptoms of strabismus include:

  • Misalignment of the gaze of one of the eyes.

  • Poor vision in one of the eyes due to lack of use.

A child may cover or close the affected eye to see clearly and hold his or her head at an angle. Left untreated, strabismus may cause amblyopia, in which the vision in the affected eye does not develop normally.


The gaze of this child’s eyes is misaligned, a disorder known as strabismus, causing conflicting images to be sent to the brain.

What might be done?

The doctor will arrange for your child to have vision tests (see Vision tests in children). If the strabismus has developed suddenly, an imaging test, such as CT scanning, may be performed to look for a tumour.

The aim of treatment is to correct the strabismus. If your child has a vision disorder such as myopia, he or she may have to wear glasses, which should also correct strabismus. To treat amblyopia, your child may also be given a patch to wear over the unaffected eye for a period of time each day. Wearing the eye patch forces the child to use the weaker eye, which is essential for the normal development of vision. Your child will have regular checkups every 3 or 6 months until the strabismus is corrected. The treatment is usually successful, although the condition can recur. In some cases, surgery on the eye muscles may be necessary. A rare underlying cause, such as a tumour, will be treated if possible.

Test: Vision Tests in Children

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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