“Lazy” eye, also known as amblyopia, is an early childhood condition in which a child’s eyesight does not develop as it should in one eye.
When a person has amblyopia, the brain focuses on one eye more than the other, virtually ignoring the lazy eye. If that eye does not receive proper stimulation, the nerve cells responsible for vision do not mature as they should.
In the United States, amblyopia affects approximately
The term “lazy eye” is misleading because the eye is not lazy. The condition is a developmental problem in the nerve connecting the eye to the brain, not a problem in the eye itself.
Fast facts on amblyopia
- Symptoms of lazy eye include blurred vision and poor depth perception.
- It is a problem with the connections between the eye and brain, not the eye itself.
- A number of factors can cause amblyopia, including a muscle imbalance or eye disease.
- Treatment can be effective, and the sooner it begins, the better.
There are three main types of amblyopia, including:
- Refractive: This shows large differences in vision between both eyes.
- Strabismic: This type causes constant eye turn in one eye.
- Deprivation: This reduces vision in one eye due to physical problems in the eye, such as a cataract.
Anything that obstructs vision in either eye during a child’s development can cause a lazy eye. Although the reasons are not clear, the brain suppresses the images coming from the most affected eye.
Below are examples of some possible causes:
Strabismus is an imbalance in the muscles that position the eye that causes the eyes to cross or turn out. The muscle imbalance makes it difficult for both eyes to track objects together. People may inherit strabismus, resulting from far- or nearsightedness, a viral illness, or an injury.
A refractive error is when the light is not correctly focused as it travels through the lens of the eye. Refractive errors occur due to nearsightedness, farsightedness, or astigmatism, in which the surface of the cornea or lens is uneven, causing blurred vision.
A child with anisometropic amblyopia will be more farsighted or nearsighted in one eye than the other, resulting in amblyopia developing in the eye most affected.
Stimulus deprivation amblyopia
This type is the least common form of amblyopia. When something prevents an eye from seeing, it becomes weaker. Sometimes, both eyes could be affected.
This type of amblyopia could be due to:
- a corneal ulcer, a scar, or another eye disease
- a congenital cataract, in which a baby is born with clouding of the lens
- ptosis, or a droopy eyelid
- eye injury
- eye surgery
Treatment tends to be more effective the younger the child is.
After a child is 8 years old, the likelihood of vision improvement drops significantly, but treatment can still be effective.
There are two approaches to lazy eye treatment. A doctor can treat the underlying eye problem or attempt to get the affected eye to work so that vision can develop.
Treatment for underlying eye problems
Many children with unequal vision or anisometropia do not know they have an eye problem because the stronger eye and the brain compensate for the shortfall. The weak eye gets progressively weaker, and amblyopia develops. Treatment includes:
Doctors will prescribe glasses to a child with nearsightedness, farsightedness, or astigmatism. The child will have to wear the glasses all the time so that the specialist can monitor how effective they are at improving the vision problems in the lazy eye. Glasses may also correct an eye turn. Sometimes, glasses can solve amblyopia, and no more treatment is required.
It is not uncommon for children to complain that their vision is better when they don’t wear glasses. Caregivers may need to encourage them to wear them for the treatment to be effective.
Cataract surgery, or phacoemulsification
If a cataract is the cause of amblyopia, doctors can surgically remove it under either local or general anesthesia.
Correcting droopy eyelids
For some people, amblyopia results from an eyelid that blocks the vision of the weaker eye. In this case, the usual treatment is surgery to lift the eyelid.
Getting the lazy eye to work
Once the vision is corrected and any underlying medical issues addressed, several other actions can help improve vision.
Occlusion, or using a patch
A doctor will place a patch over the stronger eye so that the lazy eye has to work. As the brain is only getting information from that eye, it will not ignore it. A patch won’t get rid of an eye turn, but it will improve vision in the lazy eye.
The length of treatment depends on many factors, including the child’s age, the severity of their condition, and how much they adhere to the specialist’s instructions. They usually wear the patch for a few hours each day. Caregivers should encourage a child to do close-up activities while wearing the patch, such as reading, coloring, or schoolwork.
Atropine eye drops
Doctors may use these to blur vision in the unaffected eye. Atropine dilates the pupil, resulting in blurring when looking at things close up. This makes the lazy eye work more. Atropine is usually less conspicuous and awkward for the child than a patch and can be as effective. Doctors may prescribe drops to children who cannot tolerate wearing a patch.
Different exercises and games aim to improve vision development in the child’s affected eye. Experts say this is helpful for older children. They may do vision exercises in combination with other treatments.
Sometimes, doctors perform eye surgery to improve the appearance of an eye turn, resulting in better alignment of the eyes. This may or may not improve vision.
Exercises to help correct vision are known as orthoptics. However, there are no specific exercises that can help to improve amblyopia.
During exercises, with a patch covering the stronger eye, the weaker eye is stimulated with a range of vision-intensive activities, such as coloring, dot-to-dot drawing, word games, or building Lego, depending on the child’s age.
Once strength has returned to the weaker eye, the child may do other exercises like home-based pencil pushups. These exercises involve slowly moving a pencil towards the tip of the nose and focusing on the end of the pencil during this movement until it becomes blurry.
However, doctors are unlikely to use home-based exercises as a first-line treatment for people with amblyopia. Many orthoptic exercises require vision in both eyes and can help people with different vision problems.
A child with amblyopia will not be able to focus properly with one of their eyes.
The other eye will make up for the problem, so much so that the affected eye suffers as a result.
The eye with impaired vision will not receive clear images. The brain will not receive clear data and will eventually start to ignore it.
In many cases, the brain and the stronger eye make up for the shortfall so well that the child does not notice they have a problem. That is why a lazy eye is often only diagnosed when the child has a routine eye test.
Symptoms of a lazy eye may include:
- blurred vision
- double vision
- weak depth perception
- eyes that do not appear to work together
- an eye turn, either upward, downward, outward, or inward
A child needs to have a vision check, especially if a family history of crossed eyes, childhood cataracts, or other eye conditions. If a person sees their child’s eye wandering after a few weeks old, they should speak with a doctor.
Early diagnosis is essential, preferably before the age of 6. Because the child often does not realize there is a problem, this is not always possible.
Routine eye examination
Between the ages of 3–5, a child should have a thorough eye examination to ensure their vision is developing properly and there is no evidence of eye disease. This means that doctors diagnose and subsequently treat most cases of amblyopia.
If the ophthalmologist or optometrist suspects the child has a lazy eye, they will conduct further tests before diagnosing.
They test each eye separately to determine whether there is any near- or farsightedness and how serious it is. They will also test the child carefully to determine whether there is an eye turn.
Certain complications can occur with amblyopia, including:
- Blindness: If untreated, the person may eventually lose vision in the affected eye. This vision loss is usually permanent. According to the National Eye Institute, lazy eye is the
most common causeof single-eye vision impairment in young and middle-aged adults in the U.S.
- Eye turn: Strabismus, where the eyes are not aligned, can become permanent.
- Central vision: If children do not receive treatment for amblyopia, their central vision may not develop correctly. This may affect their ability to do certain tasks.
Although amblyopia affects a small proportion of children in the U.S., it is important that a child has routine eye checks. That way, a doctor can treat amblyopia or any other eye condition early.
Several treatments are in place to help with a lazy eye, including glasses, an eye patch, vision exercises, or surgery in some cases.