Strabismus is a misalignment of one or both eyes. It can be present at birth, or may develop later in life. Strabismus is sometimes incorrectly referred to as “lazy eye” or “squint”.
What causes strabismus?
You may recall from the eye section that there are several muscles that control eye movements. These muscles are controlled by nerves that originate in the brain.
Strabismus may be caused by problems with the muscles controlling eye movements, or with the nerves controlling the muscles. Genetics are thought to play a major role in strabismus, meaning that there is often a history of strabismus in the family.
The movement of our eyes is controlled by these 6 muscles attaching to the eye. Strabismus may be caused by problems with these muscles, or the nerves controlling them.
What are some common types of strabismus?
Esotropia is an in-turning of the eyes. It can be present at birth or develop in the preschool years. Glasses may help in some cases.
The diagram shows a patient with esotropia (in-turning) of the right eye (left side of image).
Exotropia is an out-turning of the eyes. It is less common than esotropia. Exotropia develops gradually and in its early stages and may only affect the child when he/she is tired, day dreaming or sick. With time, it may increase in severity and require an operation.
Why is it important that strabismus be treated?
If the degree of strabismus is significant, it is important that it be treated. There are several reasons for this:
• Cosmetic concerns
• Amblyopia: amblyopia is a loss of vision in an eye without anatomical damage. If strabismus is present in childhood, the child will predominantly use one eye, and ambylopia can occur in the other eye.
• Loss of depth perception: one of the key ways we are able to judge distances is by focusing both eyes on the same object. In strabismus, both eyes are not focused on the same point and depth perception will be impaired.
How is strabismus treated?
If strabismus is mild, use of special eye glasses or prisms can be effective in treatment. However, many people with significant strabismus require surgery. In strabismus surgery, the length of the muscles controlling eye movement is changed to realign the eye. (to read more about strabismus surgery click here). There are no eye exercises to correct strabismus.
If amblyopia is present, it should also be treated. This is most commonly done by covering the “good eye” with a patch so that the patient is forced to use the “bad eye”.
Who treats strabismus?
The treatment of strabismus can involve many members of the health care team. This may involve pediatric ophthalmologists, orthoptists, optometrists, opticians, technicians and nurses.
A pediatric ophthalmologist is an ophthalmologist who has completed extra training in working with children. There are many eye diseases that are unique to children, as well as eye diseases that present differently in children.
