Amblyopia, often called lazy eye, is a reduction of vision in one eye that is not correctable with glasses.

There are 5 types of amblyopia:

  • Anisometropic amblyopia—Vision in one eye differs from the other. This is often caused by a large difference in eyeglass prescription. The difference may be caused by one eye being more nearsighted or farsighted than the other, or by large differences in astigmatism .
  • Strabismic amblyopia— Visible misalignment (crossing) of one eye
  • Stimulus deprivation amblyopia— Blockage of vision due to something in the eye, like a cataract
  • Ametropic amblyopia— Poor vision in both eyes
  • Meridional amblyopia— Astigmatism of both eyes
Strabismic Amblyopia
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Amblyopia is caused 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.

Genetic and environmental factors do not cause amblyopia.

Risk Factors

Amblyopia is more common in children under 10 years old with:

  • Crossed eyes
  • A large difference in sight between the 2 eyes that may be:
    • Unnoticed
    • Detected by a large difference in eyeglass prescription
  • Visual blockage such as a cataract, droopy eyelid, or corneal scarring

Amblyopia can also occur in adults.


Some people with amblyopia may not have symptoms. In those with symptoms, amblyopia may cause:

  • Blurry vision
  • Excessive squinting or closing of the eyes
  • Repeatedly closing one eye in bright sunlight
  • Crossing one eye, generally the eye that is less used will turn toward the nose

Symptoms vary depending on severity.


You will be asked about your symptoms and medical history. An eye exam will be done. Since amblyopia tends to occur in young children, the tests performed will depend on age and ability to respond.

Tests to evaluate the eyes may include:

  • Visual acuity assessment testing (VAT)—to assess distant vision
  • Cycloplegic refraction test—to assess how the eyeball displays and receives images produced by the lens of the eye
  • Retinoscopy—to determine a preverbal child’s eyeglass prescription
  • Prisms—to determine the amount of crossing between the 2 eyes


The sooner amblyopia is treated, the more favorable the outcome.

Treatment includes correcting visual obstructions, such as cataracts and other visual abnormalities.

Talk to your doctor about the best option for you. These may include:

Atropine Penalization

Atropine drops or ointment is placed in the non-amblyopic eye. This causes the sound eye to become unfocused and forces the use of the lazy eye.

Occlusive Therapy

Occlusive therapy involves using a patch over the unaffected eye, forcing the use of the lazy eye.

Bangerter foils are another option. The foils, which are made of thin vinyl, are placed over an eye glass lens, covering the unaffected eye. Just like with the patch, this forces the weaker eye to become stronger.


While there are no current guidelines to prevent amblyopia, vision screening can help to detect the condition at an early age. Children under age 3-5 years should be examined for eye problems.

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