What is strabismus?

Strabismus (say "struh-BIZ-mus") is a vision problem in which both eyes do not look at the same point at the same time. Strabismus most often begins in early childhood. It is sometimes called crossed-eyes, walleye, or squint.

What causes strabismus?

Childhood strabismus often has no known cause, although it tends to run in families.

Normally, the muscles surrounding each eye work together to move both eyes in the same direction at the same time. Strabismus occurs when the eye muscles do not work properly to control eye movement. When the eye muscles do not work correctly, the eyes may become misaligned, and the brain may not be able to merge the two images.

Sometimes strabismus develops when the eyes compensate for other vision problems, such as farsightedness.

Adults may develop strabismus from eye or blood vessel damage. Loss of vision, an eye or brain tumor, Graves' disease, stroke, and various muscle and nerve disorders can also cause strabismus in an adult.

What are the symptoms?

The most common visible sign of strabismus is when a child's eyes do not look at the same point in space at the same time. Squinting, closing one eye in bright sunlight, and tilting or turning the head to look at an object are also possible signs of strabismus.

A child with strabismus may also complain about blurred vision, tired eyes, and sensitivity to light. Double vision often occurs when strabismus first develops.

How is strabismus diagnosed?

A doctor can often tell that a child has strabismus just by looking at his or her eyes. It may be obvious that the eyes do not look in the same direction at the same time.

The doctor may have the child look at an object while covering and then uncovering each eye. This allows the doctor to determine which eye turns, how much it turns, and under what circumstances the abnormal turn occurs. These tests will also help the doctor determine whether the child has amblyopia, an eye condition also known as lazy eye in which one eye is not used enough for the visual system in the brain to develop properly.

See a picture of strabismus.

How is it treated?

The most common treatments for strabismus are the use of glasses, patches, medicines, and surgery. Wearing glasses can sometimes correct strabismus when the eyes are only slightly misaligned. Using an eye patch and medicines may improve amblyopia. Resolving amblyopia may help the eyes to align because they would be used equally, allowing them both to focus on one object. In some cases, eye exercises may be helpful.

Surgery is often the only way to correct severe strabismus. During surgery, the doctor changes the length or position of the muscles around the eye to help it align better.

Will your child outgrow strabismus?

A child rarely outgrows strabismus once it has developed. Without treatment, strabismus can cause permanent vision problems. For example, if the child is not using one eye because it is misaligned, he or she can develop poor vision in that eye (called lazy eye or amblyopia).

A newborn's eyes may initially be misaligned, but the eyes should become aligned by 3 to 4 months of age. In some cases, the eyes may simply seem to be misaligned because the child has a wide bridge of the nose that creates the appearance of crossed eyes (pseudostrabismus).

Any child older than 4 months whose eyes are not aligned all of the time should have an eye exam by an ophthalmologist. This exam should be done sooner if there is an obvious problem.

What can increase your child's risk of strabismus?

Risk factors for childhood strabismus include:

• A family history of strabismus.
• Vision problems, such as farsightedness.
• Muscle and nerve disorders (such as multiple sclerosis, myasthenia gravis, or cerebral palsy).
• Down syndrome.
• Cataract.
• Tumor in the brain or eye.
• Premature birth, low birth weight, birth injury, or newborn problems.
• Head injury.
• Infections, such as meningitis or measles.

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