Topic Overview

What is amblyopia?

Amblyopia is a childhood problem that happens when one eye is weaker than the other. The brain chooses to take in images from the stronger eye and ignore images from the weaker eye. This means that your child uses the strong eye more than the weak eye. If the weak eye doesn’t have to work, it isn’t able to develop good vision. This leads to poor vision in the weaker eye.

Amblyopia usually affects only one eye.

The problem starts between birth and about age 7. Your child may not even know that he or she is using only one eye. Ignoring the images from the weak eye is an automatic response. Your child has no control over it.

Early treatment usually can reverse amblyopia. The younger your child is when treatment starts, the more likely your child is to have good vision.

Amblyopia is sometimes called "lazy eye."

What causes amblyopia?

Any condition that prevents your child's eyes from forming a clear, focused image or that prevents the normal use of one or both eyes can cause amblyopia. It may happen when:

• The eyes do not focus on the same object. This is called strabismus. For example, one eye may point straight while the other looks in another direction. This sends two different images to the brain. In a young child who has strabismus, the brain chooses to receive the images from only one eye.
• Your child is much more nearsighted or farsighted in one eye than in the other. If one eye sees much more clearly than the other, the brain ignores the blurry image from the weaker eye.
• A problem prevents light from entering the eye for a long period of time. A problem in the lens, such as a cataract, or in the clear "window" at the front of the eye (the cornea) may cause amblyopia. These types of problems are rare but serious. Without early treatment, your child may never develop normal vision in the affected eye.

Your child may be more likely to have amblyopia if someone else in your family had it or if your child had a premature birth or low birth weight.

What are the symptoms?

In most cases, amblyopia does not cause symptoms. But your child may:

• Have an eye that wanders or does not move with the other eye.
• Have eyes that do not move in the same direction or fix on the same point.
• Cry or complain when one eye is covered.
• Squint or tilt the head to look at something.
• Have an upper eyelid that droops.