Health Library

What Is Amblyopia?

Amblyopia (am-blee-OH-pee-uh) — or “lazy eye” — is a condition in which the eye and brain don’t work together as they should. Kids who have it will develop poor vision in one or both eyes.

Kids often get used to this vision problem and might not mention it to parents. As a result, their amblyopia might not be diagnosed for years.

Often, the solution is as easy as visiting the eye doctor. Treatment for amblyopia can correct the way the eye and brain work together and strengthen vision. Early treatment is important. Waiting or not getting a proper diagnosis could lead to permanent vision loss later in life.

What Happens in Amblyopia?

From birth until around age 8, a child’s eyes and brain form vital connections. Anything that blocks or blurs vision in one or both eyes can slow down and prevent these connections.

If that happens, the brain might not fully recognize the images seen by one or both eyes. Then, the brain begins to ignore the images seen by the otherwise healthy eye, and the eye becomes weaker, losing vision strength (acuity). This eye is then referred to as “amblyopic.”

What Causes Amblyopia?

Several things can interfere with normal brain–eye connections and lead to amblyopia, including:

• Strabismus: One of the most common problems is strabismus, in which one or both eyes wander in (“cross-eyed”), out, up, or down. When eyes don’t line up together, the straight or straighter eye becomes more dominant. The vision of the straight eye stays normal because the eye and its connection to the brain are working normally. The misaligned eye doesn’t focus properly and the brain ignores its signal, eventually leading to amblyopia.
• Deprivation: Not all kids with amblyopia will have crossed or wandering eyes. Amblyopia can be due to an anatomical or structural problem that interferes with or blocks vision, such as a droopy eyelid or a cataract.
• Refractive error: Other causes of amblyopia are severe far-sightedness (hyperopia), near-sightedness (myopia), or astigmatism (a form of blurry vision). These problems make vision blurry, and it’s these blurry images that are sent to the brain. The brain never gets used to seeing a perfectly clear image, resulting in amblyopia in one or both eyes. Having different vision strengths in each eye, known as anisometropia, also can cause amblyopia. When one eye sees more clearly than the other, the brain ignores the blurry eye.

What Are the Signs & Symptoms of Amblyopia?

Most children with amblyopia won’t complain of vision problems.

Often, a parent or teacher might realize that a child is struggling with a vision problem. They might notice a child has crossed eyes, squints a lot, or tilts their head to see better. Some kids will have noticeably poor depth perception.

Regular vision screenings by health care providers are an important part of finding any vision problems in kids.

How Is Amblyopia Treated?

Treatment for amblyopia involves forcing the brain to pay attention to the images of the amblyopic or weaker eye so vision in that eye gets stronger. This is done with glasses, eye patches, eye drops, surgery, or a combination of these:

• Glasses: Glasses are prescribed when amblyopia is caused by severe refractive errors and/or anisometropia (when one eye sees more clearly than the other). Glasses help send clear, focused images to the brain, which teach it to “switch on” the weak eye or eyes. This allows the brain to use the eyes together and develop normal vision.
• Eye patches: In many cases, kids with amblyopia must wear an eye patch over the stronger or unaffected eye. The patch is worn for 2–6 hours a day while the child is awake for several months or years, depending on the condition.

  Making sure a child wears the eye patch can be a challenge. But kids usually adapt well, and the patch simply becomes part of their day. In the meantime, distraction with a new or exciting toy, a trip to the park, or just playing outside can help kids forget they’re wearing an eye patch.

• Atropine drops: Just as a patch blocks the vision in the unaffected or straight eye, atropine drops temporarily blur out the vision in the stronger eye, forcing the brain to recognize the images seen by the weaker eye. Atropine works well in cases of mild or moderate amblyopia but not as much when it is severe.
• Surgery: If strabismus (wandering eye) is causing amblyopia and treatment with glasses, patches, or drops doesn’t improve the alignment of the eyes, eye muscle surgery might be an option. Surgery also might be done if amblyopia is caused by a droopy eyelid or a cataract.

  Surgery involves loosening or tightening the muscles causing the eye to wander. This type of surgery usually doesn’t require an overnight hospital stay.

What Else Should I Know?

Kids reach visual maturity by about 8 years old. After that, vision problems can be harder to treat. The earlier amblyopia is diagnosed and treated, the better the chances to improve vision and avoid permanent vision loss.

Eye Exams for Kids

Sometimes there are no signs of a vision problem. That is why it is so important for kids to have yearly vision screenings with their pediatrician or at school. These exams should begin in the toddler and preschool years so that problems are caught before a child reaches visual maturity. It is also recommended that kids go to a local ophthalmologist or optometrist who is trained and comfortable seeing children for periodic comprehensive eye exams.

Talk with your doctor if you have any questions about your child’s vision.