Merck Manual

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(Squint; Cross-Eye; Wandering Eye)


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Last full review/revision Oct 2019| Content last modified Oct 2019
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Topic Resources

What is strabismus?

Strabismus is having one eye that looks in a different direction than the other eye. The eye may look outward (called walleye) or inward (called cross-eyes).

What causes strabismus?

Strabismus is caused by:

  • Blurry vision (farsightedness)

  • Uneven pull of the muscles that control the position of the eyes, causing them to point in different directions

  • Paralysis or weakness of a nerve that controls eye movement

  • A birth defect of the eyes

Children are at higher risk of strabismus if they:

  • Were born too early (premature)

  • Have people in their family with strabismus

  • Have certain inherited disorders such as Down syndrome

  • Their mother used drugs or alcohol while she was pregnant

What are the symptoms of strabismus?

You may notice:

  • Your child squints a lot or covers one eye

  • Your child's eyes look like they don't point the same way

  • Your child complains of eye strain, neck strain, or double vision

Because visual signals from the two eyes don't match, your child's brain starts to ignore signals from the affected eye. This causes a form of vision loss called amblyopia Amblyopia Amblyopia (also called lazy eye) is a particular kind of vision loss in children. If the images sent to the brain by each eye don't match, then the brain ignores what one of the eyes sees. Amblyopia... read more . If your child's strabismus isn't corrected before about 8 years old, the vision loss may be permanent.

How can doctors tell if my child has strabismus?

How do doctors treat strabismus?

If your child has strabismus, an eye doctor (ophthalmologist) can decide what treatment might be needed. Strabismus that's mild or comes and goes may not need to be treated. Treatment aims to align the eyes so they're looking in the same direction and see equally well. Depending on the cause and symptoms of your child's strabismus, doctors may:

  • Prescribe eyeglasses or contact lenses

  • Have the child do eye exercises

  • Sometimes, do surgery to loosen or tighten the eye muscles so the eyes can align

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