Lazy Eye (Amblyopia)

Written by Kathryn Whitbourne
Medically Reviewed by Zilpah Sheikh, MD on October 08, 2024
8 min read

Lazy eye is when the vision in one of your eyes doesn’t develop the way it should, resulting in blurred vision in that eye. Doctors also call the condition amblyopia. Without treatment, your brain will learn to ignore the image that comes from the weaker eye and it will get "lazy" from lack of use.

This could cause permanent vision problems. Amblyopia (pronounced am-blee-oh-pee-a) is the main cause of vision loss in children. It affects 2%-4% of children worldwide.

Fortunately, the condition is very treatable. 

A lot of people confuse the two conditions but they're quite different.

Strabismus is commonly known as crossed eyes. This means your eyes point in different directions, particularly when you're tired or stressed. It usually starts in childhood. Sometimes, children who have it will squint in bright sunlight. Because the eyes are looking in two different directions, the brain finds it hard to combine the images from both eyes into one 3D image.

There are different types of strabismus. In some types, the eyes turn in, while in others, they turn out, upward, or downward. Strabismus can lead to amblyopia if untreated. About 50% of children with strabismus get some type of vision loss due to amblyopia.

It can be easy to spot strabismus, while amblyopia is not so easy for a layperson to see. In either case, you'll need a vision test for confirmation.

You don't grow out of strabismus. It has to be treated, usually by surgery, which is followed by vision therapy to train the eyes to work together.

The main types of amblyopia are refractive, strabismic, visual deprivation, and occlusion.

Refractive amblyopia

This happens when vision problems such as farsightedness (hyperopia), nearsightedness (myopia), or astigmatism (unusually shaped cornea or lens) aren't corrected, leading to problems seeing. You're more likely to get these problems with farsightedness or astigmatism than with nearsightedness. That's because if you're nearsighted, you can focus clearly on nearby objects. Sometimes, there's a big difference between the sight in each eye.

Strabismic amblyopia 

Strabismic amblyopia is another name for strabismus or crossed eyes. This occurs when the eyes don't align properly, so the brain ignores input from one eye to avoid double vision. This can cause you to have problems developing binocular vision, or the ability for both eyes to work together. The two eyes might be turned in different directions.

Visual deprivation amblyopia

This happens when something blocks the normal visual input to the eye, such as cataracts, scarring of the cornea, living in complete darkness, or having your eyes covered for a long time. This condition is relatively rare and hard to treat.

Occlusion or reverse amblyopia

This occurs when the stronger or healthier eye is covered for too long or treated for too long with eye drops while being treated for lazy eye. Research shows that vision in the healthy eye can get worse if you wear an eye patch for more than 6 hours a day over 6 months. This rare condition can be reversed once you stop wearing the patch or getting the drops.

Amblyopia starts in childhood, usually between ages 6 and 9. Identifying and treating it before age 7 brings the best chances of fully correcting the condition.

Common symptoms include:

  • Trouble telling how near or far away something is (depth perception)
  • Squinting or shutting one eye
  • Head tilting

Doctors don’t always know what’s behind some cases of amblyopia. Causes may include:

Refractive errors. One eye might have much better focus than the other. The other eye could be nearsighted, farsighted, or have astigmatism. When your brain gets both a blurry image and a clear one, it starts to ignore the blurry one. If this goes on for months or years, vision in the blurry eye will get worse.

Strabismus. This is when your eyes don’t line up the way they should. One could turn in or out. People who have strabismus can’t focus their eyes together on an image, so they often see double. Your brain will ignore the image from the eye that isn’t aligned.

Cataracts. A cloudy lens inside your eye can make things look blurry, affecting vision in that eye.

Droopy eyelid (ptosis). A sagging eyelid can block your vision.

 

 

A child might be more likely to have a lazy eye if they:

  • Were born early (premature)
  • Were smaller than average at birth
  • Have a family history of amblyopia or other eye conditions
  • Have developmental disabilities

All children should have vision tests before they are school-age. Your child's doctor or the vision program at school (if there is one) will check to make sure that:

  • Nothing blocks the light coming into their eyes
  • Both eyes see equally well
  • Each eye moves the way it should

If there's any problem, the doctor or school nurse may suggest that you take your child to an eye specialist. If you feel like something is wrong with your child's vision — even if nothing shows up at the vision check — make an appointment with a pediatric eye doctor.

Some eye care experts say kids should get an eye exam at 6 months old, 3 years old, and then every year while they’re in school. Ask your doctor what’s right for your child.

Eye doctors test babies and young children by watching how well their eyes follow a moving object. They may also cover one eye at a time and check the child’s reaction.

In older kids, the doctor will cover one eye and use pictures and letters to check their vision.

It’s important to start treatment for amblyopia as soon as possible. Depending on the cause, it might involve:

  • Correcting any underlying vision problems such as nearsightedness, farsightedness, or astigmatism. Most kids with amblyopia also need glasses to help their eyes focus.
  • Surgery, if a cataract is blocking light from their eye or if strabismus keeps their eyes from moving together the way they should
  • Wearing a patch over the strong eye to force their brain to use the weak one. Your child will have to wear it usually 2-6 hours a day. At first, they'll have a hard time seeing. But their vision will get better, though it might take weeks or months. After that, they won’t have to wear the patch. If they start to lose some vision in the weak eye, they might have to wear the patch again.
  • Eye drops with a medication called atropine, which blurs the strong eye so your child won’t need to wear a patch. This also forces their brain to use the weaker eye.
  • A Bangerter filter, which is worn over the eyeglass lens of the stronger eye to blur its vision, encouraging use of the weak eye

Amblyopia surgery

There is no surgery for lazy eye. Usually, when people say this, they're thinking of surgery for strabismus or crossed eyes. That surgery either loosens or tightens the eye muscles so the eyes are aligned. It has a very high success rate.

Some people are born with ptosis (droopy eyelids) and others get it as they age. If you have ptosis and it's causing amblyopia, you can have surgery to tighten the muscle that raises your eyelids.

Normally, laser eye surgery (also known as LASIK) can't correct amblyopia. However, laser eye surgery may help if the vision in one eye is normal and the other is nearsighted or farsighted, a condition called anisometropia. In this type of surgery, a laser beam is used to reshape your cornea and bring your vision to normal in one or both eyes.

Traditionally, it was thought that older teens and adults couldn't improve their lazy eye because their brains weren't as adaptable. Plasticity of the brain decreases as a person ages. It's best to treat amblyopia before a child’s vision has fully developed (at around age 7 to 9), but lazy eye can be treated in older children and adults.

Recent studies have shown that giving standard vision therapies to adults with amblyopia, such as eye patching,  did help improve their vision, even if not to the level of younger kids. Your brain can still adapt at later ages. And adults may be more likely to go along with the required treatment and exercises than young children.

So, if you weren't treated for lazy eye as a kid, see your eye doctor for help. They can prescribe exercises and activities to improve your vision. You could have major problems if you don't get treated for lazy eye and you lose vision in your stronger eye later in life.

The main complication if treatment starts too late (or not at all) is a permanent loss of vision in the weaker eye because links in the body’s visual system won’t form properly. This can mean problems such as:

  • Lower sharpness of vision
  • Difficulty seeing contrast
  • Trouble seeing fine details
  • Difficulty perceiving depth and space
  • Inability to use both eyes together, which affects the ability to see in 3D 

Children with amblyopia may have learning difficulties, read more slowly, and take longer to answer questions than children who don't have it. Adults with amblyopia may have problems holding some kinds of jobs.

With early diagnosis and treatment, most children will regain almost all their vision. Make sure your child gets eye exams early on. Follow your doctor's advice about treatment, even when it’s hard to make your child do things such as wear a patch every day.

Amblyopia (lazy eye) happens when one eye has blurry vision and the other has clear vision. Over time, without treatment, the brain will focus on the eye with clear vision and ignore the one with blurry vision. As the brain ignores the weaker eye, that vision gets worse. It affects very young children and is not something they can control. Treatment usually consists of wearing an eye patch over the stronger eye to encourage use of the weaker eye. Sometimes, eye drops that blur vision in the stronger eye are used instead.

Can amblyopia be cured?

Yes, if it's caught early. If it's not diagnosed until you're an older child, teen, or adult, treatment will take longer and may not be as effective.

Is lazy eye a disability?

That probably depends on how much amblyopia affects your ability to perform your job. For more information, see this link from the U.S. Equal Employment Opportunity Commission.

Why did I develop a lazy eye?

It's nothing you can control. It doesn't mean you're lazy. It's a condition where you're born with misaligned eyes. However, children who were born prematurely, with low birth weight and have family members with vision problems are more likely to have lazy eye.

Print
View privacy policy, copyright and trust info
View privacy policy, copyright and trust info