United Kingdom
Change

Support and offers for individual members and customers

Health Information

Lazy eye (amblyopia)

Published by Bupa's health information team, July 2009.

This factsheet is for parents of children who have a lazy eye, or who would like information about it.

A lazy eye is when the sight in one of your child's eyes is poor because the brain is ignoring the information coming from it. A lazy eye usually only affects one eye but It is possible for it to affect both.

It's thought that up to one in 25 children have a lazy eye.

About lazy eye
Symptoms of lazy eye
Complications of lazy eye
Causes of lazy eye
Diagnosis of lazy eye
Treatment for lazy eye
Questions and answers
Related topics
Further information
Sources

About lazy eye

A lazy eye develops when there is a fault in the eye (and brain) during early infancy or childhood that stops visual stimulation being received properly. It is also called amblyopia.

A child's vision isn't fully developed at birth and the brain needs time to 'learn' to understand the information coming from the eyes. This process is usually complete at eight years of age. A lazy eye isn't necessarily a disease or condition affecting the eye itself, rather a problem with the development of vision by your child's brain.

When your child looks at an object, an image is picked up by each eye. This information is sent to the brain and turned into one image. Each provides slightly different information about the object, this enables your child to judge depth.

If the visual image from one eye is markedly different to that from the other, for example, if the eyes aren't aligned properly or the image is blurred, the brain starts to ignore the poor image and uses just the image from the good eye. The eye that is ignored is called a lazy eye.

If your child has a lazy eye, he or she will still be able to see the world in three dimensions, but their overall depth perception (stereopsis) may be reduced. This may not be an immediate concern. However, it can cause problems when doing some sports and, in later life, may make certain careers impossible (for example, pilot). Also, relying on vision in one eye alone could lead to serious sight problems if vision in the good eye is affected later in life.

Symptoms of lazy eye

Often there are no symptoms for a lazy eye and your child will not even realise there's anything wrong with his or her vision. However, you may spot signs that your child is having difficulty seeing properly or other features of conditions that can cause a lazy eye.

Younger children usually just accept having one good eye and one poor eye but may object to having their good eye covered. Older children may complain that their vision is much worse in one eye than the other.

One eye may look in a different direction to the other (a squint) and you may notice that your child adopts a particular head position to compensate for this.

Depending on the underlying cause of the lazy eye, it's possible you might notice that one of your child's eyes looks different from the other: one eyelid may droop down more than the other (a ptosis) or there may be noticeable clouding in one eye (for example, a cataract).

Complications of lazy eye

Leaving a lazy eye untreated may result in your child being permanently unable to see out of their affected eye. This can affect your child's fine perception of depth and may result in a squint. Occasionally, development of vision in both your child's eyes may be affected.

A lazy eye is usually permanent by the age of seven or eight. After this time, it becomes much more difficult to reverse the changes in your child's vision.

Underlying causes of a lazy eye may occasionally have broader health implications and require prompt treatment.

Causes of lazy eye

The visual information from one of your child's eyes may be ignored by the brain as a result of the following eye conditions.

Squint. A squint is when the muscles that control eye movement are out of balance. This means that one eye looks forward at the object in focus, whereas the other eye turns away (usually either outwards or inwards).
Anisometropia. This is when there is unequal vision in each eye as a result of long-sightedness, short-sightedness or astigmatism (refractive errors). This means that one eye is able to focus on the object your child is looking at while the other eye can't.
Iso-ametropia. This is when there is a high level of symmetrical long-sightedness or short-sightedness in both eyes (usually long-sightedness) resulting in an unfocused image at the back of the eye.
Ptosis. Ptosis is a condition affecting the muscles in the eyelid causing it to droop down. This means that one eyelid droops downward blocking some of the vision in that eye, while the other eyelid is open as normal with full vision.
Cataract. A cataract is a clouding in the lens of the eye. If a child is born with a cataract it's called a congenital cataract.
An injury affecting vision in one eye only.
Birth defects affecting the light sensitive part of the eye (the retina) or the nerve that transmits signals from the retina to the brain (optic nerve).

Diagnosis of lazy eye

Your GP will refer your child to an orthoptist or an ophthalmologist. An orthoptist is a health professional who specialises in eye movement problems such as squints, lazy eyes and double vision. An ophthalmologist is a doctor who specialises in eye heath, including eye surgery.

Your child's orthoptist will carry out routine assessments using specialised techniques to determine whether your child is at the right stage of visual development. Often orthoptists undertake screening at pre-school to pick up children who would otherwise go untreated.

Your child's ophthalmologist will carry out a detailed examination of your child's eyes to exclude any other causes of poor vision. If it's suspected that you child has a lazy eye or is at high risk of developing it, he or she may need monitoring for several years.

Even if your child has been seen before regarding their sight, it's still worth seeking advice if you have any concerns about their vision.

Treatment for lazy eye

It's important to get treatment for your child's lazy eye as early as possible. After about the age of eight, the condition may not respond to treatment.

The success of treatment for your child's lazy eye will depend on the underlying cause, their age, their level of vision at diagnosis and how carefully they stick to their treatment plan.

Your child may only need to wear a pair of glasses (or sometimes contact lenses). These will correct the blurring caused by any refractive error in the affected eye, or help stop your child's eyes from squinting. It's important to try to ensure that your child wears his or her glasses as instructed by your orthoptist or ophthalmologist and to report back any problems.

More involved treatment aims to force the lazy eye to start working again. This is done by covering or blurring the vision in your child's good eye using either a patch (occlusion) or, less frequently, eye drops and ointments (penalisation). Occasionally, glasses or contact lenses may be used to blur vision in your child's good eye.

Your child may need to wear the eye patch or use penalisation for several hours a day over many weeks or months.

There is a risk that the good eye may become lazy if it is covered up too much or for too long. Your orthoptist or ophthalmologist will monitor your child's progress carefully and adjust treatment accordingly, but it's important to follow the instructions given and to report back any concerns. Getting a child to wear a patch over his or her good eye can be hard work. If the treatment proves too difficult, talk to your orthoptist or ophthalmologist about other options.

Any conditions found to be causing your child's lazy eye will also be treated or monitored by your ophthalmologist.