In the United States, about 2 to 3 in every 100 children experience amblyopia, more commonly known as a lazy eye. Adults may also experience this condition, but it is most common up to 7 years of age.

Amblyopia is signified by a wandering eye, squinting, eyes that don’t work together, or head tilting. (Read More)

One eye may have a lesser ability to focus compared to the other. (Learn More) Rarely, the condition can affect both eyes.

There are treatment options, particularly for children, that can be beneficial for helping to alleviate the condition. (Learn More) Treatment for adults can be a bit trickier.

Prior to exploring treatment options, a definitive diagnosis is necessary. (Learn More)

Signs & Symptoms

Amblyopia is typically associated with vision development in infants, so the symptoms and signs can sometimes be hard to discern.

Strabismus is when a...

Strabismus is when a baby or child is cross-eyed; essentially, the eyes do not align properly. Strabismus is a common cause of amblyopia.

Parents may notice an eye misalignment. If the child becomes fussy when one eye is covered, this can also indicate that they have amblyopia.

Other possible symptoms may include:

  • One of the eyes wanders outward or inward.
  • Poor depth perception.
  • Head tilting.
  • The eyes look like they are not working together.
  • Shutting of an eye or squinting.
  • Abnormal test results on a vision screening.

In most cases, only one eye is affected, but it is possible for both eyes to have amblyopia.

Possible Causes

vector of ambylopia

There are three primary causes of this condition.

  • Refractive errors
  • Strabismus
  • Cataracts

A refractive error is when the eye’s shape prevents the proper bending of light once it enters the eye. The primary types of refractive errors are:

  • People with this error are unable to clearly see objects that are close.
  • When this error is present, vision may be distorted, causing objects to look wavy or overall blurriness.
  • People with this error are unable to clearly see objects in the distance.
  • This error occurs because the lens of the eye loses flexibility due to aging. People find it harder to read things that are close.

Strabismus is a condition that is characterized by the eyes being crossed. The eyes do not work together properly, and they are unable to maintain proper alignment. There are different types, including.

  • Crossed eyes (esotropia).
  • Downward-turned eyes (hypotropia).
  • Upward-turned eyes (hypertropia).
  • Eyes that turn outward (exotropia).

Cataracts are characterized by the lens of the eye developing a clouding. While most cataracts occur in older adults, it is possible for them to develop at any age. When cataracts occur in a baby, they are called congenital cataracts. In many cases, cataracts will develop on both of the child’s eyes.

There are certain risk factors that may make it more likely for someone to develop amblyopia, such as:

  • Small size at birth.
  • Developmental disabilities.
  • Premature birth.
  • A family history of amblyopia.

Refractive Amblyopia

The most common cause of amblyopia are refractive errors that are uncorrected. There are two types of refractive amblyopia.

  • Anisometropic amblyopia: This type is a kind of unilateral amblyopia. It occurs when each eye has a distinct refractive error.
  • Isoametropic amblyopia: This type occurs when amblyopia affects both eyes due to a similar and significant refractive error. It is a bilateral amblyopia.

The anisometropic type is likely when there is 2.0 D or more anisoastigmatism, 1.0 to 1.5 D or more anisohyperopia, or 3.0 to 4.0 D or more anisomyopia.

The isoametropic type is likely in the presence of 4.0 to 5.0 D or more hyperopia, 5.0 to 6.0 D or more myopia, or 2.0 to 3.0 D or more astigmatism.

When significant astigmatism is the cause of amblyopia, it is called meridional amblyopia.

Diagnostic Testing

Early diagnosis is important. If parents notice anything odd with their child’s eyes, they should visit an eye doctor as soon as possible. In general, children should visit a doctor around 6 months of age to get a comprehensive optometric examination.

With early treatment, vision issues in an eye with amblyopia can be adjusted. Often, the child’s vision can be fully corrected.

During a comprehensive eye exam, the doctor will do the following:

  • Take a complete patient history, including information about family history.
  • Test for visual acuity, usually via the Snellen test.
  • Evaluate depth perception, eye muscle movement, pupil response to light, color vision, and peripheral vision.
  • Look at the cornea’s curvature using keratometry.
  • Conduct eye teaming, focusing, and movement testing.
  • Do refraction testing to evaluate how much lens power is needed to compensate for various refractive errors that may be present. This is done using a variety of lenses and a phoropter.

If a doctor suspects amblyopia, they may do additional testing to get an accurate diagnosis. If the person is an infant or small child, the parent will play a major role in answering questions and providing information that is important to ensure an accurate diagnosis.

  • If the child is at least 3 years old, letters and pictures can be used to evaluate their vision. During the testing, each eye is assessed individually by using an eye patch.
  • For kids under age 3, the doctor can use a magnifying device with a light to look for cataracts. Other assessments may be performed to look at the child’s gaze, their ability to fixate, and how well they can follow an object that is moving.

Treatment Options

child with eyepatch for ambylopia

The underlying cause of amblyopia and the condition’s ultimate effect on vision determine the course of treatment. There are various possible treatment methods.

  • Corrective eyewear, such as contact lenses or eyeglasses, may be prescribed to people who have refractive errors. These will aid with overall vision.
  • Bangerter filters, which go onto an eyeglass lens, may be used. This is placed on the eyeglass lens of the eye that is stronger. The purpose is to blur this eye so the weaker eye is stimulated.
  • Eyedrops might be helpful. They can blur the eye that is stronger to help the weaker eye build strength.
  • The weaker eye can be stimulated by patching the stronger one.
  • In some cases, surgery may help. If the eye muscles are playing a role in this condition, and other methods aren’t effective, surgery may be the next step.

For children, certain activities might be helpful. Puzzles, drawing, and various computer games can all help to strengthen the eyes. These can be used with traditional treatment methods.

Treatment can last 6 to 24 months. Many people notice an improvement in their symptoms within weeks to months.

Even after treatment, it is possible for amblyopia to recur.

It is imperative to receive prompt treatment for this condition. If amblyopia goes untreated, there is a risk for permanent vision loss. In approximately 2.9 percent of adults with permanent vision loss, amblyopia is the cause.

Consult with an optometrist or ophthalmologist if amblyopia is suspected.


Facts About Amblyopia. (September 2013). National Eye Institute.

Types of Amblyopia. (October 2015). American Academy of Ophthalmology.

Amblyopia. All About Vision.

Amblyopia. MedlinePlus.

Amblyopia (Lazy Eye). Prevent Blindness.

Amblyopia (Lazy Eye). American Optometric Association.

Lazy Eye (Amblyopia). Mayo Clinic.

Refractive Errors. Kellogg Eye Center.

Comprehensive Eye and Vision Examination. American Optometric Association.

Strabismus and Crossed Eyes. All About Vision.

Facts About Cataracts. National Eye Institute.

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