Lazy Eye (Amblyopia): Causes, Symptoms and Treatment

Lazy eye is one way to describe amblyopia, a childhood vision condition in which one eye is underdeveloped. Sometimes both eyes are affected.

Amblyopia can appear as a wandering eye, crossed eyes or eyes that do not seem to work together.

It typically affects kids between the ages of 6 and 9. The earlier it is diagnosed, the sooner treatment can begin, and the soon treatment starts the better the long-term prognosis is.

What Is a Lazy Eye? 

Lazy eye, also known as amblyopia, or lazy vision, is a mostly early childhood condition that occurs when the vision of one of your eyes does not develop as it should. The condition develops when there is a breakdown in how the brain and the eye work together.

The brain focuses with the better eye and ignores the lazy eye. If the lazy eye is not then stimulated enough, nerve cells responsible for vision do not mature as they should, which makes the weaker eye get worse over time and can result in permanent vision problems. 

The condition is called “lazy eye” because the stronger eye works better while the other eye seems like it cannot keep up. 

Amblyopia generally develops from infancy to childhood, usually between ages 6 and 9, and is the leading cause of decreased vision among children. In rare cases, lazy eye affects both eyes.

Early diagnosis and treatment are vital as they can help prevent long-term vision problems. Treatments include the use of glasses or contact lenses or patching therapy. 

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Symptoms of Lazy Eye (Amblyopia)

A lazy eye is not always obvious. The condition can go undetected until the child has an eye test or it becomes severe. 

The signs and symptoms of lazy eye include:

• An eye that wanders inward or outward
• Eyes that appear not to work together 
• Poor depth perception 
• A tendency to bump into objects on one side 
• Head tilting
• Squinting or shutting an eye 
• Double vision 
• Abnormal results of vision screening tests 

Causes of Lazy Eye (Amblyopia)

Lazy eye develops because of abnormal visual experience that changes the nerve pathways between the retina and the brain. As a result, the weaker eye receives fewer visual signals. Eventually, the eye’s ability to work together decreases and the brain ignores input from the weaker eye. 

Conditions that may cause abnormal visual experience and result in amblyopia include: 

• Refractive errors
• Strabismus
• Structural problems

Refractive Errors

These conditions affect how light passes through the eye and include:

• Nearsightedness (myopia, trouble seeing far away)
• Farsightedness (hyperopia, trouble seeing up close)
• Astigmatism (curved cornea)

Strabismus

This is the most common cause of lazy eye and involves an imbalance in the muscles that position the eyes. This imbalance can cause the eyes to turn out or cross in and prevents them from working together as a pair. If one eye drifts, up, down, in or out, the brain may tend to rely on the other eye leading to amblyopia. 

Structural Problems

Some structural problems affecting the eye can lead to amblyopia including:

• Cataracts 
• Astigmatism
• Droopy eyelid (ptosis)
• Scar on the cornea
• Eye surgery
• Eye injury
• Glaucoma

Risk Factors Associated with Lazy Eye (Amblyopia)

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

• Were born prematurely
• They were smaller than average at birth
• They have developmental disabilities
• They have a family history of amblyopia or other eye conditions 

Diagnosing Lazy Eye (Amblyopia) 

Amblyopia usually occurs in only one eye. When it first occurs, the signs and symptoms may not be apparent to the child or to the parent.

Therefore, it is important to have routine eye exams for your infant and child. The American Optometric Association recommends that children have eye exams at six months of age and again before they are 3 years old to ensure that their vision is developing properly. Early diagnosis increases the chances of a full recovery. 

The pediatrician, school vision program, opthamologist or optometrist will typically perform a standard eye exam to assess vision in both eyes. The tests might include:

• Identifying shapes or letters on a chart 
• Following a light with one and then both of your eyes 
• Having your doctor look at the eyes with a magnifying device 

These series of tests determine:

• If the eyes allow will light all the way through
• If the eyes move correctly and together
• If both eyes see and focus equally well 
• If the eyes are properly aligned 
• If one eye drift or wanders 
• If there is a difference in vision between the two eyes 
• If there are any cataracts visible

For most amblyopia diagnoses, an eye examination is all that is required. 

Complications Associated with Lazy Eye (Amblyopia)

Certain complications can result from amblyopia. Among them are:

• Blindness
• Eye turn
• Central vision

Blindness

If the condition is left untreated, or treatment starts too late, the patient may permanently lose vision in the affected eye. The National Eye Institute reports that lazy eye is the most common cause of single eye vision impairment in young and middle-aged adults in the United States.

Eye Turn

Strabismus, a condition where the eyes do not move together in unison, may become permanent.  

Central Vision

If children fail to receive treatment for amblyopia, or treatment is delayed, their central vision may not develop properly which could affect their ability to perform certain tasks. 

Treatment Options for Lazy Eye (Amblyopia)

It is important to start treatment for lazy eye as soon as possible in childhood when the connections between the eye and the brain are still forming. The best treatment results occur when treatment starts before age 7, although around 50 percent of children between ages 7 and 17 also respond well to treatment.

Treatment options depend on the underlying cause of lazy eye and on how much the condition is affecting vision. 

Surgical Treatment Options for Lazy Eye

Cataract Surgery or Phacoemulsification

If the lazy eye is caused by a cataract, doctors can surgically remove the cataract under local or general anesthesia. 

Correcting Droopy Eyelids (Ptosis)

In some cases, lazy eye could be a result of an eyelid blocking the vision of the weaker eye. The usual treatment for this situation is surgery to lift the eyelid. 

Surgery

Doctors may also perform a surgery to improve the appearance of an eye turn (Strabismus) and to straighten the eyes. This procedure can be in addition to other lazy eye treatments.

Non-Surgical Treatment Options for Lazy Eye

Non-surgical treatments for lazy eye are:

• Corrective eyeglasses
• Eye patches or occlusions
• Atropine eye drops
• Bangerter Filter
• Vision exercises

Corrective Eyewear

Glasses or contact lenses can be prescribed to correct vision problems such as nearsightedness, farsightedness or astigmatism that can result in amblyopia.

It is common for children to complain that their vision is better when they don’t wear the corrective eyewear. As such, caregivers need to encourage them to wear their corrective eyewear for the treatment to take effect.  

Eye Patches or Occlusions

Your child will be required to wear an eye patch over the better eye for two to six hours or more in a day in order to stimulate the weaker eye. Treatment can last month or even years depending on the child’s age, severity of their condition and how well they adhere to the doctor’s instructions.

The patch forces the brain to use the images from the weaker eye, eventually making the weaker eye to have better vision although it will not get rid of an eye turn.

In rare cases, wearing an eye patch for too long can cause amblyopia to develop in the previously better eye that has been patched. However, this is usually reversible. 

Atropine Eye Drops

Atropine (Isopto Atropine) dilates the pupil resulting in blurring when looking at things that are close. Doctors may use these drops to blur vision in the better eye which forces the lazy eye work more. 

Atropine drops are a less conspicuous and awkward treatment option for children and can be as equally effective as a patch. 

Bangerter Filter

This special filter is placed over the eyeglass lens of the stronger eye to blur its vision and stimulate the weaker eye as is the case with an eye patch.

Vision Exercises

There are different games and exercises that aim to improve vision development in the affected eye. These exercises are particularly helpful for older children and can be used in combination with the other treatments. Some of the vision exercises you could try:

• Color in the lines
• Do puzzles while wearing a patch over the stronger eye
• Hold a pencil close to your nose, move it away then back in close again as you focus on the near tip while it moves.
• Read while wearing a patch over the stronger eye

Living with Amblyopia

Although amblyopia only affects a small portion of children in the United States, it is important that your child has routine eye checks. With early diagnosis and treatment, children with amblyopia can significantly improve their vision.

The goal of treatment is to improve sight as much as possible even though it may not lead to perfect sight especially in severe cases. Combine these treatments with vision exercises to strengthen the eye. 

Whatever combination of treatment or therapies you decide to use, stick to it for maximum effect.

It is important to remember that amblyopia does not go away on its own. If left untreated, amblyopia can result in permanent vision loss or a “wonky eye” that is always facing a different direction. 

Resources for Families with Visual Impairments

A family dealing with visual impairments can often struggle to understand the condition, it’s treatment and its general outlook. The Vision of Children Foundation offers a comprehensive list of resources pertaining to support and education.

The first place to turn for help with vision impairment is to call an eye doctor or find a vision specialist near you.

References

1. Amblyopia (Lazy Eye). (July 2019). The National Eye Institute.

2. Amblyopia. (January 2021). American Association for Pediatric Ophthalmology & Strabismus

3. Lazy eye. (May 2019). National Health Services

4. Amblyopia: What Is Lazy Eye? (September 2021). American Academy of Ophthalmology

5. Common Eye Disorders and Diseases. (June 2020). Centers for Disease Control and Prevention.

6. See the Full Picture of Your Health with an Annual Comprehensive Eye Exam. (October 2018). American Optometric Association.

7. Amblyopia: Lazy Eye Diagnosis & Treatment. (September 2021). American Academy of Ophthalmology.

8. Amblyopia. (September 2009). The British Medical Journal.

9. Lazy Eye (Amblyopia). (March 2019). Harvard Health Publishing; Harvard Medical School

10. Astigmatism. (March 2019). Harvard Medical School.

11. Amblyopia (Lazy Eye). (October 2020). Cleveland Clinic.

12. Resources for Parents with Visually Impaired Children. (May 2018). Vision of Children Foundation.