Amblyopia: Definition, Types, Symptoms, Causes, Diagnosis, Treatment, Investigation and Outlook

You probably know this childhood eye condition by its more common name, lazy eye.

It happens when the vision in one of your child’s eyes does not develop as it should.

If left untreated, your child’s brain will learn to ignore the image coming from that eye. That could permanently damage your vision.

Amblyopia or lazy eye is a common eye condition found in about 1 in 30 people. It is usually caused by an undetected need for glasses in an infant or young child, but it can result from an eye roll.

When one eye has regular sight, and the other has poor eyesight, the person learns to see through the eye with good company. Vision in the weaker eye does not grow and develops as the child grows. This can affect the ability of both eyes to coordinate efficiently.

Some children seem unaffected by this when they are young, but they may have problems with school and athletic performance when they are older.

If left untreated, amblyopia can affect a child’s self-image, work, school, and friendships and lead to depression.


Amblyopia produces a lack of depth perception and teaming in the eyes, focus, and tracking. These difficulties can result in struggles at school or uncertainty in daily activities and sports.

Later in life, an adult with amblyopia may be restricted in the careers of their choice.

Office-based vision therapy programs offer the highest cure rates for lazy eyes compared to eye surgery, lenses alone, or patches without therapy.

Children do not want to wear the eye patch because it affects their quality of life, and other treatment methods such as eye drops can cause sensitivity to light and disorientation.

As a result, amblyopia does not always go away with patch therapy alone.

Even the patient who has undergone patch therapy will generally have a condition known as suppression. The amblyopic eye turns off, resulting in stereo blindness and poor depth perception, prone to accidents, and poor eye coordination. -hand.

The first step is to get a pair of glasses or goggles that can be worn comfortably. This starts correcting the original problem in one eye so that you can see more clearly than the other.

So the ability for the two eyes to work together as a team must be developed through an individualized vision therapy program. The person may still need glasses after completing the vision therapy program.

The goal is for the patient to have normal vision, eye teaming, eye-focus, and eye movement skills.

The earlier the condition is found and treated, the better the functional outcome; however, our office successfully treats patients into adulthood.

Vision therapy should be started with anyone who does not have 20/20 vision with glasses or contact lenses in each eye or anyone who has impairments in any visual skills necessary for visible success.

Types and symptoms

Amblyopia has three leading causes:

Strabismus : due to strabismus (misaligned eyes).

Refractive: by anisometropia (difference of a certain degree of myopia, hyperopia, or astigmatism) or by an equal refractive error in both eyes.

Private: from vision deprivation early in life from disorders that obstruct vision, such as congenital cataracts.

Amblyopia extremism

Strabismus, sometimes also incorrectly called lazy eye, is a condition in which the eyes are misaligned.

Strabismus usually results in normal vision in the preferred observing (or ‘companion’) eye (the eye the person likes to use). Still, it can cause abnormal vision in the deviated eye or strabismus due to the difference between the images projected to both eyes’ brains.

Adult-onset strabismus usually causes double vision (diplopia), as the two eyes are not fixed on the same object.

However, children’s brains are more neuroplastic, so they can more easily adapt by suppressing images from one of the eyes, eliminating double vision.

However, this plastic response of the brain disrupts normal brain development, resulting in amblyopia. Recent evidence points to a cause of infantile strabismus that lies with the entrance to the visual cortex.

Those with strabismic amblyopia tend to show eye movement deficits when reading, even when using the non-adlopopic eye.

In particular, they tend to do more pulls per line than people with normal stereoscopic vision and have a reduced reading speed, especially when reading text with small font size.

Stanbic amblyopia is treated by clarifying the visual image with glasses or by encouraging the use of the amblyopic eye with a patch on the dominant eye or the pharmacological penalty of a better look.

The penalty generally consists of applying atropine drops to temporarily paralyze the accommodation reflex, leading to blurred vision in the good eye.

It also dilates the pupil. Although applying eye drops is sometimes challenging, this helps prevent bullying and teasing associated with wearing a patch.

The ocular alignment itself can be managed with surgical or non-surgical methods, depending on the type and severity of the strabismus.

Refractive or anisometropic amblyopia

Refractive amblyopia can result from anisometropia (uneven refractive error between the two eyes).

Anisometropia exists when there is a difference in power between the two eyes. The eye that provides the brain with a more precise image typically becomes the dominant eye.

The image in the other eye is blurred, resulting in the abnormal development of one-half of the visual system.

Refractive amblyopia is usually less severe than strabismic amblyopia. Primary care physicians often overlook it because of its less dramatic appearance and lack of apparent physical manifestation, as with strabismus.

Since the refractive correction of anisometropia using glasses generally leads to a different image magnification for the two eyes, which can prevent binocular vision, a refractive correction with contact lenses should be considered.

Pediatric refractive surgery is also a treatment option, notably if conventional approaches have failed due to aniseikonia or non-compliance.

Amblyopia is often associated with a combination of anisometropia and strabismus. In some cases, the vision between the eyes may differ where one eye has twice the average idea while the other eye is completely blind.

Privatization and occlusive amblyopia

Withdrawal amblyopia (amblyopia ex anopsia) occurs when the visual media becomes opaque, as in the case of congenital cataract or corneal clouding.

These opacities prevent adequate visual input from reaching the eye and disrupt development. If not treated promptly, amblyopia can persist even after removing the cause of the clouding.

Sometimes a drooping eyelid (ptosis) or some other problem causes the upper eyelid to physically occlude a child’s vision, which can quickly cause amblyopia.

Amblyopia due to occlusion can be a complication of a hemangioma that blocks part or all of the eye.

Other possible causes of occlusion deprivation and amblyopia include vitreous obstruction and aphakia. Deprivation amblyopia accounts for less than 3% of all people affected by amblyopia.

What causes it?

Amblyopia usually begins when one eye has much better focus than the other. Sometimes one has more farsightedness or astigmatism, but the other does not.

When your child’s brain gets both a blurry and a clear image, it begins to ignore the blurriness. If this continues for months or years in a young child, the vision in the blurry eye will worsen.

Sometimes a child’s eyes don’t line up the way they should. One could go in or out. The doctor will call this strabismus, which can also lead to amblyopia. Children who have it cannot focus their eyes on one image, so they often see twice as much.

If your child has it, his brain will ignore the eye image that is not aligned. The vision in that eye will get worse. It is this misalignment that led to the term “lazy eye.”

Some children cannot see well with one eye because something is blocking the passage of light. It could be a cataract or a small amount of blood or other material at the back of the eye.

How is amblyopia diagnosed?

All children should be tested before reaching school age. Your child’s doctor or the vision program at the school will verify that:

  • Nothing blocks the light that enters your eyes.
  • Both eyes see equally well.
  • Each eye moves as it should.

If there are any problems, your doctor or school nurse may suggest taking you to an eye doctor. If you feel that something is wrong with your child’s vision, even if nothing shows up on the eye exam, make an appointment with a pediatric eye doctor.

Some eye care experts say that children should have an eye exam at six months, three years, and then every year while they are in school. Ask your doctor what is suitable for your child.

If the family has amblyopia, your child is more likely to have it. Remember, you can’t tell just by looking at her if she has it. Early diagnosis and treatment are the keys to getting good results.

How is it treated?

The most common method is to force your child’s brain to start using the weak eye. First, the doctor will correct any underlying problems in that eye, such as nearsightedness, farsightedness, or astigmatism.

Most children with amblyopia also need glasses to help focus their eyes. If a cataract blocks the light from your eye, your doctor may recommend surgery to remove it.

Follow the doctor’s instructions carefully and take your child to scheduled visits so the doctor can see how the treatment is working.

In mild cases of amblyopia, the doctor may suggest using an eye drop called atropine. Erase the strong eye, so your child does not need to wear a patch.

If strabismus keeps your eyes from moving the way they should, your doctor may recommend surgery on your eye muscles. You can talk about which treatment is best for her.

Treatment of anisometropia and refractive errors should occur next. The amblyopic eye must have the most precise optical correction possible. This should happen before any occlusion therapy because vision can improve with glasses alone.

This improvement is frequently seen in patients with unilateral refractive amblyopia.

Complete cycloplegic refraction should be administered to patients with accommodative esotropia and amblyopia. A prescription less than the complete plus refracted measurement may be prescribed in other patients since the decrease in plus is symmetrical between the two eyes.

Because the accommodative range is believed to be decreased in amblyopic eyes, care must be taken to reduce the amount too much. Refractive correction alone has improved amblyopia in up to a quarter of patients in a nationwide trial.

Patients with bilateral refractive amblyopia do well with spectacle correction alone, with most 3- to 10-year-olds achieving 20/25 or more within a year.

The next step is to force the use of the amblyopic eye through occlusion therapy. Occlusion therapy has been the foundation of a treatment since the 18th century. The following are general guidelines for occlusion therapy:

Patches can be full-time or part-time. The standard teaching has been that children should be observed at intervals of 1 week per year if they undergo occlusion full time to avoid occlusive amblyopia in the good eye.

Amblyopia Treatment Studies (ATS) have helped provide new information on the effect of various amounts of patches.

Always consider non-compliance in a child where visual acuity is not improving. Compliance is difficult to measure, but it is an essential factor in determining the success of this therapy.

In addition to adhesive patches, opaque contact lenses, eyeglass-mounted occluders, and eyeglass tape were used.

It is essential to establish that the vision of the better eye has degraded sufficiently with the chosen therapy.

Amblyopia treatment studies have helped define the role of the full-time patch versus the part-time patch in patients with amblyopia.

Studies have shown that, in patients aged 3-7 years with severe amblyopia (visual acuity between 20/100 and 20/400), full-time patching produced an effect similar to 6 hours of patching per day.

In a separate study, 2 hours of daily patches improved visual acuity similar to 6 hours of daily patches when treating moderate amblyopia (visual acuity better than 20/100) in children aged 3 to 7 years.

In this study, the patch was prescribed with 1 hour of close visual activities.

Data from amblyopia treatment studies are also available for older patients, although patients younger than seven years are the best responders to treatment.

For patients between 7 and 12 years old, studies of treatment with amblyopia suggest that prescribing 2 to 6 hours a day of patching can improve visual acuity, even if the amblyopia has been previously treated.

Among patients aged 13-17 years, the prescription of 2-6 hours a day of patch improves vision in 47% of patients whose amblyopia had not been previously treated and improves vision in 25% of patients whose amblyopia had previously been treated with patches.

Studies have also found that about a quarter of children with amblyopia who have successfully treated experience a recurrence within the first year after stopping treatment.

Data from these studies suggest that patients treated with six or more hours per day of patching are at increased risk of recurrence when the patch is stopped abruptly rather than when it is reduced to 2 hours per day before the patch is stopped.

There is some evidence that having children wear an eye patch for 6 hours a day instead of 2 hours can lead to a more significant improvement in visual acuity at ten weeks.

The significantly more significant improvement in visual acuity seen with the more intense patching protocol suggests that this strategy is worth considering in children with residual amblyopia. The results have the following implications:

If there is stable residual amblyopia after 12 weeks of 2-hour patching, an increase to the 6-hour patch may produce further improvement.

If the goal is to achieve the best result in the shortest amount of time, it may be worth skipping the 2-hour patch and starting with the 6-hour patch.

In the past, penalty therapy was reserved for children who did not wear a patch or where compliance was an issue.

Amblyopia treatment studies, however, have shown that the atropine penalty in patients with moderate amblyopia (defined by the study as visual acuity better than 20/100) is as effective as a patch.

Amblyopia treatment studies were conducted in children aged 3 to 7 years.

Amblyopia treatment studies have also shown that weekend atropine use improved visual acuity similar to daily atropine use when treating moderate amblyopia in 3- to 7-year-old children.

Atropine drops or ointment are instilled into the non-amblyopic eye. This therapy is sometimes used in conjunction with individual practitioners’ eyeglass patching or occlusion (such as tape and nail polish).

In amblyopia treatment studies evaluating patching versus atropine penalty, atropine penalty and patching were used in conjunction with 1 hour of near vision activities.

This technique can also be used for maintenance therapy, which is helpful, especially in patients with mild amblyopia.

Other options include optical blur through contact lenses or raised bifocal segments.

In a prospective cohort study of 105 children who had previously participated in a randomized trial that compared atropine and patch for moderate amblyopia.

After controlling for the initial refractive error, the researchers observed a decrease in the amblyopic equivalent spherical refractive error at less farsightedness.

This shift toward emmetropia was associated with ocular alignment, supporting the idea that better motor and sensory fusion promotes emmetropia.

The desired endpoint of therapy is a spontaneous alternation of fixation or equal visual acuity in both eyes.

When visual acuity is stable, patching may decrease slowly, depending on the child’s tendency for amblyopia to reappear.

There is no set standard for tapering the treatment of patches.

Because amblyopia recurs in many patients (see Prognosis), maintenance therapy or treatment reduction should be seriously considered.

This narrowing is controversial, so individual physicians vary in their approaches.

Although there have been many advances in the treatment of amblyopia, tailoring treatment with individual treatment plans remains challenging because the dose/effect response of the amount of occlusion is not fully understood.

Treatment of strabismus generally occurs last. The endpoint of strabismic amblyopia is a free, alternating fixation or equitable vision. Surgery is usually done when the endpoint has been reached.


Between 2 and 5% of the population in Western countries have amblyopia. In the UK, 90% of child eye appointments are related to amblyopia.

Depending on the criteria chosen for diagnosis, between 1 and 4% of children have amblyopia.


A 2009 study, widely reported in the popular press, has suggested that repetitive transcranial magnetic stimulation can temporarily improve contrast sensitivity and spatial resolution in the affected eye of adults with amblyopia.

This approach is still under development, and the results await verification by other researchers.

It has also been suggested that comparable results can be achieved using different types of brain stimulation, such as anode transcranial direct current stimulation and repetitive theta transcranial magnetic stimulation (rTMS).

A 2013 study concluded that convergent evidence indicates that uncorrelated binocular experience plays a critical role in the genesis of amblyopia and associated residual deficits.

Another 2013 study suggests that playing a version of the popular Tetris game modified so that each eye sees separate game components may also help treat this condition in adults.

Furthermore, it has been proposed that the effects of this type of therapy can be further enhanced by non-invasive brain stimulation, as shown in a recent study using transcranial anode direct current stimulation (tDCS).

A 2014 Cochrane review sought to determine the effectiveness of occlusion treatment in people with sensory deprivation amblyopia, but no trials were found eligible to be included in the review.

However, the good results of occlusion treatment for sensory deprivation amblyopia probably depend on adherence to treatment.

What is the long-term outlook?

With early diagnosis and treatment, most children will gain vision. Amblyopia becomes much more difficult to treat after age 7-9, so make sure your child has eye exams early.

And follow your doctor’s advice on treatment, even when it’s complicated. Most children don’t want to wear an eye patch every day. Ask your doctor if atropine is an option for your child.