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.
How is amblyopia diagnosed?
Your child's doctor will do an eye examination. If the examination shows that your child has poor vision in one eye, the doctor may diagnose amblyopia after ruling out other causes.
To help make the diagnosis, the doctor will ask about symptoms, any family members who have had vision problems, other possible risk factors such as low birth weight, and whether your child has trouble reading, seeing the board in school, or watching TV.
The Canadian Paediatric Society recommends screening to detect lazy eye (amblyopia), misaligned eyes (strabismus), and defects in visual acuity in children younger than 5 years of age.footnote 1 If you worry about your child's eyes or vision, take him or her to an eye doctor sooner.
How is it treated?
For amblyopia to be treated, your child must use the weak eye. This will force the eye to get stronger. Over time this corrects the vision in the weak eye.
Your doctor may suggest:
- Blocking the strong eye with an eye patch.
- Blurring the strong eye with eyedrops or glasses.
Your child may have to wear the patch or glasses most of the day or for just part of each day. Treatment may last for a few weeks or months. Severe cases may take longer.
If another problem is causing the amblyopia, such as a cataract, it also needs to be treated.
Treatment is best started before age 6 and should begin before your child's vision has fully developed, around age 9 or 10. Later treatment will most likely be less helpful but may still improve vision in some cases. A child with amblyopia who does not get treatment may have poor vision for life.
After treatment ends, be sure to set up follow-up eye examinations for your child. Amblyopia can return even after successful treatment.
How can you help your child cope with treatment?
Treatment sounds simple, but using an eye patch or glasses may bother your child. To help your child:
- Explain that the glasses or patch will help his or her vision get better.
- Tell your child's friends, teachers, coaches, and others about the eye problem and what you and your child have to do for it. Ask for their help.
- Use the patch, glasses, or eyedrops as your doctor says.
- If possible, decorate the patch with your child. First, ask your doctor if it's okay.
- Do fun things, such as colouring and crafts, when your child is wearing the patch or glasses. This will help your child use the weak eye.
Current as of: December 18, 2019
Author: Healthwise Staff
Medical Review: John Pope MD - Pediatrics
Anne C. Poinier MD - Internal Medicine
Adam Husney MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine
Christopher J. Rudnisky MD, MPH, FRCSC - Ophthalmology
Current as of: December 18, 2019