Amblyopia, or lazy eye, is when the vision in one eye doesn’t develop as it should. This causes the weaker, or lazy eye to wander inward or outward.

Amblyopia begins during infancy or childhood. Over time, the brain favors the stronger eye, while vision in the lazy eye gets worse. The good news is that early treatment can increase the chances of full recovery.

In this post, we will talk about the different types of amblyopia and their causes. We also have a list of early symptoms to look out for. Plus, you can learn about how amblyopia is diagnosed and treated.

But before we begin, let’s understand the amblyopia definition better.

What Is Amblyopia?

Amblyopia, more commonly known as lazy eye, is poor vision in one eye. It starts during childhood, when the brain and eye don’t work together as they should. As a result, the brain starts relying more on the dominant eye, ignoring the weaker one. Eventually, this may cause permanent vision loss.

The “lazy eye” is not really lazy. But it may wander in different directions—inward, outward, upward, or downward. Note that this condition isn’t the same as crossed or turned eye.

Amblyopia usually affects only one eye. But both eyes can also become amblyopic in certain cases.

Important: The condition is easily treatable if diagnosed early. So, make sure you get your child’s eye examined regularly.

Amblyopia in Children

Is your child often squinting while reading? Does he struggle while playing tennis, unsure when to hit the ball? Is she showing signs of clumsiness, often bumping into things on one side? Your child may have amblyopia.

Amblyopia usually starts in childhood. It’s one of the most common vision disorders in children. According to the US National Eye Institute, about 3 in 100 children have lazy eye.

The amblyopic eye does not look any different from the other eye. But your child may complain of blurred vision in one eye. Or he/she may have a poor perception of depth. You may also notice a wandering eye or a constant squint.

Sometimes, children with amblyopia may not show any outward symptoms. But routine eye exams can uncover the condition. A prompt diagnosis and treatment can fully correct your child’s eye.

Amblyopia in Adults

If left undiagnosed during childhood, amblyopia can cause reduced vision in adults. And it isn’t always correctable with just eyeglasses or contact lenses.

That’s because vision loss is caused by a poor eye and brain connection. In other words, the brain simply ignores the visuals from the weaker eye. Adults with amblyopia suffer from two common symptoms: poor depth perception and headaches.

Although easier to correct in childhood, amblyopia in adults is also treatable. It requires a combination of vision therapy, prescription lenses, and sometimes patching.

These strategies help train the weaker eye and develop better binocular vision (in which both eyes work together).

Good to know: While amblyopia is usually diagnosed in childhood, in rarer cases, some people may not become aware they have the condition until they are adults.

blue iris in the corner of the eye closeup photo

Types of Amblyopia

There are three types of amblyopia. These are refractive, strabismic, and deprivation. All three cause reduced vision in the weaker eye. They may also occur at the same time in one single eye.

Refractive Amblyopia

This is the most common type of amblyopia. But it’s also the hardest to recognize. In refractive amblyopia, there is a large difference in vision between both eyes.

Your child may see well from the dominant eye, while the brain turns off vision from the weaker eye. He or she may not even complain of blurry vision. And the condition can easily go unnoticed for a long time.

Strabismic Amblyopia

In this, a squint develops in one eye. It’s easier to diagnose than refractive amblyopia, as the eye constantly turns in, out, up, or down. When this happens, the brain begins to ignore vision from the wandering eye. As a result, vision in that eye drops.

Deprivation Amblyopia

This is the least common type of amblyopia. But also the most severe. In this, your child’s eye is deprived of visual experience. This may be due to physical problems in the eye, such as a cataract or ptosis. If not treated early, your child may never learn to see clearly with that eye.

Amblyopia Causes

Lazy eye occurs when there’s an interference in the brain-eye connection. There are three causes for this: muscle imbalance, refractive error, and structural problems in the eye.

Let’s understand each of these causes better.

Muscle Imbalance

Eye muscle imbalance is a common cause of lazy eye. It occurs when the eyes do not work together as they should. The weak muscle causes one eye to drift in, out, up, or down. And the brain starts relying on one eye over the other.

Refractive Errors

Refractive errors include nearsightedness, farsightedness, and astigmatism. Any of these in one eye can cause amblyopia. If left untreated for a long time, the difference in vision between each eye will grow. And the brain will start to rely more on the eye with sharper vision.

hand holding pair of glasses in whose lens the blurry green background becomes clear

Structural Problems

Sometimes, structural problems such as cataracts, a scar on the cornea, or a droopy eyelid can also cause amblyopia. These can blur or completely block sight in one eye. And the vision in that eye might not develop as it should.

Amblyopia Risk Factors

Some kids are born with amblyopia. Others develop it during infancy or childhood. Certain factors can also increase the risk of amblyopia in your child. These include:

  • Premature birth
  • Family history of amblyopia and childhood cataracts
  • Low weight at birth
  • Developmental disabilities or delays

Lazy Eye Symptoms

Lazy eye usually starts in childhood. But it can go unnoticed for a long time as the symptoms are not always apparent. Regular eye exams can help.

Make sure to also keep a lookout for these signs of amblyopia in your child:

  • Poor depth perception, causing your child to constantly bump into things
  • Difficulty catching and throwing objects
  • Constantly rubbing one eye to see clearly
  • Eyes that don’t move in the same direction as they should
  • Clumsiness and fatigue with near work
  • An eye turning inward (crossed eye) or outward (walled eye)
  • Droopy eyelid or squint
  • Tilting head to one side
  • Blurry vision in one eye and reading difficulties

How Is Lazy Eye Diagnosed?

Amblyopia is diagnosed through a routine eye exam. The eye doctor will look for signs of a wandering eye and see if there’s a difference in vision between the eyes. Early diagnosis of amblyopia can increase the chances of a full recovery.

The method to diagnose amblyopia depends on the patient’s age.

  • Infants under 2 years: The doctor will use a lighted magnifying device to detect cataracts. Other tests involve assessing the infant’s ability to fix his or her gaze on a moving object.
  • Children over 3 years: The doctor will test the child’s vision using pictures or letters. They will also cover each eye in turn to test the other eye’s ability to focus.
  • Adults: An ophthalmologist or optometrist may notice signs of undiagnosed amblyopia during a regular eye exam.

Amblyopia Treatment

Lazy eye treatment is much more effective in childhood. That’s because the eyes and brain connections are still forming. But the right treatment can lead to positive results later in life, too.

Amblyopia treatment strengthens the brain-eye connection. This forces the child’s brain to use the weaker eye more. It involves a combination of corrective eyewear, eye patches, Bangerter filter, eyedrops, and surgery.

Corrective Eyewear

Vision problems in one eye can sometimes cause lazy eye. Your doctor will first try to correct your child’s nearsightedness, farsightedness, or astigmatism. This can be done by prescribing glasses or contact lenses, which will help the weaker eye focus better.

Eye Patches

Wearing an eye patch over the stronger eye will help stimulate the weaker eye. The length of this treatment depends from case to case. Your child will have to wear the eye patch for two to six hours each day. This will force the brain to use the lazy eye, eventually making it stronger.

Bangerter Filter

The Bangerter filter is for children who cannot tolerate eyepatches. It’s worn over the eyeglass lens of the stronger eye.

This filter must be worn full time. It helps blur the dominant eye and, like an eye patch, works to stimulate the lazy eye.

Eye Drops

Medicated eye drops can be used to blur the vision in the stronger eye. This makes the weaker eye work more. Preservative-free eye drops can be a good alternative to an eye patch, as most kids often try to pull off eye patches.

Eye drops may help treat mild cases of lazy eye, but they may cause sensitivity to light and eye irritation.

Vision Exercises

Different eye exercises can help strengthen the eye muscles. These also train the eye and brain to work together better. Combined with other treatment methods, vision exercises can show remarkable progress.

young girl playing with a jigsaw puzzle around adults

Most eye exercises can be done at home. And they aren’t even boring. Lazy eye vision exercises include putting together jigsaw puzzles, drawing pictures, or playing specially designed video games.


Surgery for lazy eye is rare. But your child may need one if the lazy eye is caused by a squint, droopy eyelid, or cataract.

Eye surgery can also help improve the cosmetic appearance of the weaker eye. This tightens or loosens the muscles causing the eye to wander.

Being Active Matters Even with a Lazy Eye

Lazy eye can be treated. Take your child for regular eye exams. And don’t forget the follow-up appointments. If your child is diagnosed with lazy eye, opt for early treatment.

Also encourage your child to wear glasses and eye patches, even though they may complain. You can offer reward points each week to keep your child motivated.

You can also create a healthy diet chart for your child. Leafy green vegetables, citrus fruits, and seeds rich in omega-3 can strengthen the eye muscles. And don’t forget to have fun with your child by reading or solving puzzles together.

If you, as an adult, think you may have undiagnosed lazy eye, don’t hesitate to get a complete eye exam. It doesn’t take long and is painless.

Lastly, don’t forget that in many cases, symptoms like blurriness or discomfort in the eye have more common causes, such as dry eye.

Dry eye is far more prevalent in adults than lazy eye. A quick online test can tell you whether your symptoms match those of dry eye.

Take the Dry Eye Test.

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