Amblyopia is a reduction of vision in one eye that cannot be corrected with glasses. It is also called lazy eye.

There are five types of amblyopia:

  • Anisometropic amblyopia—Vision in one eye differs from the other
  • Strabismic amblyopia—One eye is not aligned with the other
  • Stimulus deprivation amblyopia— Vision is blocked due to something in the eye, such as a cataract
  • Ametropic amblyopia— Poor vision in both eyes
  • Meridional amblyopia— Both eyes have an abnormal or irregular curve

Early treatment can improve outcomes.

Strabismic Amblyopia

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Amblyopia happens when the brain prefers one eye to the other. The brain’s preference can weaken and reduce vision in the eye that is less used.

Eye problems that can cause this to happen are:

  • Eyes that are not aligned
  • Having a large difference in sight between both eyes
  • Vision problems at birth, such as a cataract or droopy eyelid

Risk Factors

This problem is often noticed during childhood. Things that may raise the risk of this problem are:

  • Being born very early
  • One or both eyes that turn outward or inward


Some people may not have symptoms. Others may have:

  • Blurry vision
  • Difficulty telling how near or far an object is
  • Squinting
  • Shutting one eye when looking at things
  • Head tilting
  • Eyes that cross


The doctor will ask about your symptoms and health history. An eye exam will be done. Vision in each eye will be tested. This is often enough to make the diagnosis.


Any underlying eye problems will need to be treated, such as removing a cataract.

The goal of treatment is to correct vision. This is done by forcing the brain to use the weaker eye so that it gets stronger. This should be done as early as possible to lower the risk of lifelong vision problems.

Options are:

  • Occlusive therapy—Covering the stronger eye with a patch or covering the eyeglass lens of the stronger eye with a special type of foil
  • Atropine penalization—Blurring the vision of the stronger eye with medicated eye drops or ointment


There are no known ways to prevent this health problem.


Eye Smart—American Ophthalmology

National Eye Institute


Canadian National Institute for the Blind

Canadian Ophthalmological Society


Amblyopia. EBSCO DynaMed website. Available at: Accessed September 15, 2021.

Amblyopia (lazy eye). National Eye Institute website. Available at: Accessed September 15, 2021.

Last reviewed July 2021 by EBSCO Medical Review Board Mary-Beth Seymour, RN  Last Updated: 9/15/2021