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Strabismus occurs when the eyes are not correctly aligned and point in different directions when looking at an object. It is commonly known as ‘turned’, ‘lazy’ or ‘crossed’ eyes.

One eye or both eyes may turn either inward (esotropia), outward (exotropia), upward (hypertropia) or downward (hypotropia). Strabismus may be constant or intermittent.

Strabismus is one of the most common eye conditions in children, affecting up to 5% of the Australian population.

Causes and risk factors

Whilst the causes of strabismus are not completely understood it is known that abnormalities in the muscles and nerves surrounding the eyes are both contributing factors.

A person can be born with strabismus or develop it during infancy or childhood, or later in life. It can also occur as a result of injury to the eye or head trauma.

Sometimes strabismus can be a sign of a more serious eye disease or other health problem, and should always be thoroughly investigated by an eye specialist as soon as possible.

Early diagnosis is essential in preventing vision loss.


Amblyopia, commonly known as ‘lazy eye’, is the loss of vision caused by strabismus if left untreated. When a person with a strabismus looks at an object the brain receives two different images and this can confuse the brain. In children, the brain may learn to ignore the double image from the turned eye. This constant ignoring of the image from one eye during a child’s visual development can result in poor vision. Untreated, the vision will remain poor.

In most cases amblyopia can be successfully treated before the age of nine, it is therefore important to diagnose and treat this condition early on.

3D Vision

Strabismus and amblyopia can also interfere with the development of 3D vision (depth perception). Early treatment can improve the likelihood of depth perception developing in a young child.


The symptoms of strabismus may be constant or intermittent, and include;

  • crossed eyes,
  • double vision,
  • uncoordinated eye movements,
  • vision loss,
  • loss of depth perception.

Strabismus can be difficult to detect in children, particularly if the size of the turn is small and not cosmetically noticeable. If a child is showing any signs of strabismus they should be examined by an eye specialist immediately.


Early diagnosis of strabismus is essential in preventing irreversible vision loss later in life. Strabismus treatment aims to improve the alignment of the eyes and to correct the resulting vision loss (amblyopia).
Strabismus and amblyopia can be treated with any one or a combination of glasses, eye patching or surgery.

The Lions Eye Institute understands that every child’s case is different to another, with its own set of unique challenges. Therefore, tailored treatment strategies for each child are established.

The Lions Eye Institute also conducts an array of Clinical Trials. You can view these on our Clinical Trials page.

Strabismus surgery

Surgery involves moving one or more of the eye muscles in order to adjust the position of the eye(s). The procedure is undertaken in an operating room under a general anesthetic. There are no bandages, with only mild discomfort and redness for a few days. Usually, the patient is ready to go home on the same day.

Australian and international references


Strabismus Inheritance Study

Who is conducting the study?

Professor David Mackey from the Lions Eye Institute and Professor Elizabeth Engle at Children’s Hospital Boston, in conjunction with ophthalmologists from across Australia and the USA. The project is being coordinated by the research team at the Centre for Eye Research Australia (CERA).

Purpose of the study

The research team are investigating the possible genes involved in the development of strabismus and associated eye conditions e.g. wearing glasses, poor depth perception. Families with a strong history of strabismus are of particular interest to the research team.

For further information

The research team are recruiting participants who have, or have had, strabismus. Please contact the CERA for further information or to register your interest.

Phone: 03 9929 8713
Email: strabismus@nulllists.unimelb.edu.au

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