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Quick Facts


(Lazy Eye)


The Manual's Editorial Staff

Last full review/revision Sep 2021| Content last modified Sep 2021
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What is 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 usually starts before age 2 years, but it can happen in children up to age 8

  • Amblyopia can be caused by a focusing problem, eyes that don’t line up with each other, or a cataract (clouding of the eye lens)

  • Children may have permanent vision loss if amblyopia isn't treated by age 8

  • Doctors correct amblyopia with eyeglasses, an eye patch, or eye drops

What causes amblyopia?

Children's vision isn't fully developed at birth. Babies and young children need to see clear, focused images from each eye so that their visual pathways develop normally. The pathways don't finish developing until children are about 8 years old.

If a child's brain isn't getting good visual images from one eye, the brain starts to ignore that eye. For a while this doesn't matter. Just like if you wore an eye patch, you'd still see okay when you took it off. But if a child's brain never gets good images from one eye, then by about age 8, the child's brain can never learn to see things from that eye even if the original problem is fixed. This can lead to permanent decreased vision.

The brain might start to ignore images from one eye because:

What are the symptoms of amblyopia?

Children with amblyopia can't see well out of one eye. They may not notice they have a problem or may be too young to describe their vision problem. However, children with amblyopia may:

  • Squint or cover one eye

  • Have one eye that doesn’t look in the same direction as the other

  • Have trouble telling how far apart 2 objects are (poor depth perception), for example, have trouble catching a ball

How can doctors tell if my child has amblyopia?

To tell if your child has amblyopia or other vision problems, doctors routinely test your child's eyesight. They usually do these tests at your child's regular well-child visits, starting around age 3. Your child's eyesight should be checked throughout childhood.

If doctors think your child isn't seeing well, they'll have you take your child to an eye doctor (an ophthalmologist or an optometrist).

How do doctors treat amblyopia?

To treat amblyopia, eye doctors must train your child’s brain to use the visual images from the problem eye. They may:

  • Temporarily block vision in your child's normal eye by putting a patch over it or using eye drops to blur its vision—this forces the brain to recognize images from the problem eye

If your child has a focusing problem like farsightedness, doctors will:

  • Have your child wear eyeglasses (or sometimes contact lenses)

  • Do eye surgery

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