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What is amblyopia?

Amblyopia (say: am-blee-OH-pee-ah) means a decrease in fine vision or visual acuity (say: ak-YOO-it-ee), also known as sharpness. It happens when the brain does not fully develop the vision in the eye. Amblyopia usually happens in only one eye, but it can happen in both eyes. It is sometimes called "lazy eye".

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The brain and eyes work together to produce vision. Amblyopia is when the vision in one eye is reduced because the brain and that eye are not working together properly.

Causes of amblyopia

Amblyopia can be caused by any condition or illness that makes the eye blur an image or makes the brain prefer one eye. Common causes include:

  • strabismus (when the eyes are not positioned straight)
  • unequal eye focusing (when one eye focuses differently than the other)
  • cataract (clouding of the lens)
  • severe ptosis (droopy eyelids)
  • premature birth
  • heredity (when a child inherits amblyopia from parents with strabismus)
  • any disease that affects the eye.

Children under 9 are at the greatest risk

Children under 9 years of age are at the highest risk for amblyopia. At this age, your child's vision is still developing. Generally, the younger the child, the greater the risk.

Treatment of amblyopia

Each child's amblyopia is different. Your child's treatment will depend on his age and the cause of the amblyopia. Treatment may include eye glasses, patching, eye drops, and/or surgery. Your doctor will explain the best treatment for your child. 

Eye glasses

Your child may need eye glasses to improve his vision. These help the eyes work together and help focus images for both eyes. Eye glasses will only work if your child wears them all the time when he is awake.


Blocking the vision of your child's stronger eye with a patch helps to strengthen his lazy eye.

Your doctor will explain how often to apply the patch and how long your child will need it.  The doctor will need to check your child often to see if the treatment is working.

Eye drops

In some cases, the doctor may prescribe special drops to blur the vision in the stronger eye. This makes the lazy eye work harder. It is very important to put in the eye drops correctly.


Your child may need surgery when amblyopia happens along with:

  • strabismus
  • cataract
  • ptosis
  • other diseases of the eye.

If surgery is needed, your doctor will tell you what will happen.


If you have any questions or concerns, please call the doctor who saw your child.

Doctor's name _______________________  Phone: ___________________

Key points

  • Amblyopia, sometimes called "lazy eye", means a decrease in fine vision or visual acuity.
  • Amblyopia usually happens in one eye because the brain does not fully develop the vision in that eye.
  • Children under 9 are at the highest risk for amblyopia because their vision is still developing.
  • Treatment depends on your child's age and the cause of the amblyopia. Your doctor will explain the best treatment for your child.

At SickKids:

If the eye doctor who operated on your child's eyes is not available, call 416-813-7500 and ask for the eye doctor on call.

Yasmin Shariff, RN

Stephen Kraft, MD, FRCSC

Nasrin Najm-Tehrani, MD, FRCSC

Kamiar Mireskandari, MD, FRCSC