In some children, however, one eye is favored by the brain because it provides a better image. If this happens, the other eye is neglected from childhood on, and it does not get the chance to fully develop. This is known as amblyopia or "lazy eye." Amblyopia, the medical term for lazy eye, is taken from ancient Greek and means "dull vision."
Symptoms
If your child has a wandering eye or you think he or she may have an eye problem, it is important to have it checked out by an eye doctor. Difficulties recognizing objects might be a sign of amblyopia too. For example, if your child has to hold toys or other objects very close to their eyes or tilts their head to one side to see them better.
 |
| Source AAPOS |
Causes
Amblyopia develops when the brain keeps receiving different information from both eyes and cannot form a single image. The most common cause is strabismus (also referred to as a "squint" or "crossed eyes"). If a child has strabismus, one eye will look straight ahead while the other looks up, down or to the side.
If the eyes send two different images to the brain, the brain cannot combine these images to form one single view, resulting in double vision. The brain may start ignoring the images sent by the weaker eye to improve overall vision.
Most children who have strabismus have amblyopia: Somewhere around 60 to 70% of children with strabismus are affected by it.
Only about 2% of children who do not have strabismus have amblyopia.
Another common cause of amblyopia is refractive errors (focusing problems). There are 3 different kinds of refractive error:
- Near-sightedness (or short-sightedness): where the eye can only focus clearly on objects that are close
- Far-sightedness: where the eye can only focus clearly on objects that are far away
- Astigmatism: Everything the affected eye sees looks blurry because the lens or the cornea is deformed.
Some eye conditions may cause amblyopia in rare cases – such as cataracts, a droopy eyelid (called ptosis) or an eye without a lens (aphakia).
Frequency
Amblyopia is a common eye problem in childhood. In the USA, amblyopia is the most common cause of visual impairment among children, affecting approximately 2 to 3 out of every 100 children. In Germany, it is estimated that about 4 to 6% of children are affected. It usually does not develop after the age of 7 or 8.
Diagnosis
There are several tests that can be used to diagnose amblyopia in children:
- The doctor can use eye charts to see how good your child’s vision is. The exact kind of test will depend on several factors, including your child’s age. There are special tests for babies and toddlers.
- A test can also be done to see whether your child’s eyes are aligned properly. A slight squint is not always visible to the naked eye.
- A physical check-up can be done to see whether the poor eyesight is caused by something else, like a cataract.
- The exact refractive power of your child’s eyes can be determined using a special instrument called a retinoscope. This involves shining light into the eye and seeing how the light reflects off the retina at the back of the eye. By holding different corrective lenses in front of the light, it is possible to determine exactly how well the eye can focus.
- Once the refractive power has been determined, a further eye test can be done using an eye chart. This time the child wears glasses that correct any focusing problems he or she may have.
 |
| Retinoscope |
These tests are generally safe. Eye drops are often used before a retinoscopy examination to dilate (open) the pupils and they can sometimes cause a burning sensation in the eyes or skin irritation.
Screening
Experts agree that most of our vision develops by age five. They recommend that amblyopia be detected and treated as early as possible to prevent both life-long impaired vision as well as problems in social development.
Based on these recommendations, an additional screening test specially designed to detect amblyopia was introduced in Germany in 2008 for all preschool children with statutory insurance. In Germany, screening programs for children have names made up of "U" and a number related to the order in which they are given. U7a is the name of this test: it is intended for children about to turn three (between the ages of 24 and 36 months).
Treatment
Wearing glasses is not an immediate fix for amblyopia. But there are
different ways to help the affected eye catch up with its partner, or at
least help make sure that the problem does not get worse over time.
Treatment might only be needed for a few weeks, but sometimes it needs
to continue for quite a long time to get the best results.
Early treatment is always best. If necessary, children with refractive errors (nearsightedness, farsightedness or astigmatism) can wear glasses or contact lenses when they are as young as one week old. Children with cataracts or other “amblyogenic” conditions are usually treated promptly in order to minimize the development of amblyopia. However, it's never "toolate" to treat. A recent National Institutes of Health (NIH) study confirmed that SOME improvement in vision can be attained with amblyopia therapy initiated in younger teenagers (through age 14 years). Better treatment success is achieved when treatment starts early, however.
There are different options for treating amblyopia in children, mostly depending on the type and severity of the condition.
Some children only have one eye that focuses properly. This is known as amblyopia or "lazy eye" and is caused by the eyes sending two different images to the brain, which can happen when a child has strabismus (a squint) or is more nearsighted or farsighted in one eye than the other. The brain then ends up preferring the information coming from the stronger eye and neglecting the other.
The severity of amblyopia largely determines the kind of treatment needed. The standard treatment options are:
Children will usually first wear glasses for several weeks and then also use an eye patch. Treatment typically takes a few months, during which regular eye tests are done. Children who have refractive errors will need to keep wearing glasses in order to see clearly after treatment is completed.
If amblyopia is caused by another problem, such as a cataract, then treatment starts there. Children with severe strabismus sometimes need surgery. This kind of surgery involves tightening or relaxing the eye muscles to correct the misalignment of the eyes so that they move parallel to each other again, as far as possible. The aim is to improve spatial vision and make the condition less obvious. This surgery generally does not have anything to do with treatment for amblyopia. Sometimes amblyopia gets better without treatment, but it is not clear how often that happens.
For a long time it was widely believed that treatment is only successful if it is started early. But a comparison of two small studies involving children between the ages of 7 and 17 showed that later treatment also has a good chance of improving eyesight. Vision problems can worsen and may become permanent if amblyopia is left untreated.
Researchers from the Cochrane Collaboration – an international network of researchers – analyzed studies testing different treatments for amblyopia. They found hardly any research on treatments for amblyopia caused by strabismus. Still, there was some evidence that wearing glasses and an eye patch is more effective in improving children's vision than wearing glasses alone.
Wearing an eye patch with glasses has been shown to improve vision in children who have one amblyopic ("lazy") eye and whose eyes have different refractive powers. Generally speaking, they only need to wear the eye patch for two to six hours a day, depending on how poor their eyesight is. Sometimes wearing glasses is enough and no eye patch is needed.
Two studies compared eye patches with drug therapy, where eye drops are used once a day to numb the muscles of the healthy eye. This keeps the lens from focusing for a while. The studies showed that both treatments had similar effects.
Some people worry that patching could make the healthy eye weaker, because it is used less during the treatment. But the studies that tested eye patching treatment for amblyopia did not confirm that. Eye patches can irritate some children's skin, however.
Eye drops can have side effects like light sensitivity or stinging. This treatment may affect vision in the stronger eye for some time, but this was only temporary in the studies. Eye drops may be an option for children who find it difficult to wear an eye patch.
Children are sometimes encouraged to exercise the weaker eye by doing arts and crafts activities while wearing the eye patch. But two studies showed that this does not cause improved vision in most children. It cannot be ruled out that children who have a very "lazy" eye might benefit from that kind of exercise.
Many different factors will influence how successful the treatment is, and it is difficult to predict how things will turn out in an individual case. The child's age, the time of treatment and the type and severity of the amblyopia can all influence the results. It can take quite a long time until treatment shows some benefit, and that can be very frustrating for the child and their parents.
Most children do not have any problems wearing their eye patch in their day-to-day life. But some have a hard time wearing it as much as they are supposed to. There are several reasons for this. When their “good” eye is covered up they can only see with their weaker eye, so their vision will be worse, which can cause problems when they are playing or doing school work. Other children might tease them about the eye patch in kindergarten or at school.
Children who have to wear their eye patch for a longer time may feel more self-conscious than children who only have to wear it for a few hours a day. The doctor can let you know how many hours a day your child needs to have the patch on for it to be effective. Parents use different strategies to try to help their child cope with a patch. Some make sure their child understands why the patch is important, while others might carefully explain the results of eye tests to show that the eye is really getting stronger.
Children like to know that they are "normal." Some parents have reported that doing things like putting eye patches on toys – or even wearing patches themselves – helps make their child's eye patch feel "normal." Some parents find it helpful to also use praise or small gifts to encourage their child to wear the patch, while others think it is better to not make that big a deal out of it.
Children might not like how the patches look or think they are uninteresting. Some like covering up their glasses with something more interesting that they can pick out. Following a regular daily routine that involves wearing the patch can be important to children too, and the good news is that in a few months' time the patch will most likely be history.
Sources: Institute for Quality and Efficiency in Health Care / American Association for Pediatric Ophthalmology and Strabismus / National Eye Institute
Early treatment is always best. If necessary, children with refractive errors (nearsightedness, farsightedness or astigmatism) can wear glasses or contact lenses when they are as young as one week old. Children with cataracts or other “amblyogenic” conditions are usually treated promptly in order to minimize the development of amblyopia. However, it's never "toolate" to treat. A recent National Institutes of Health (NIH) study confirmed that SOME improvement in vision can be attained with amblyopia therapy initiated in younger teenagers (through age 14 years). Better treatment success is achieved when treatment starts early, however.
There are different options for treating amblyopia in children, mostly depending on the type and severity of the condition.
Some children only have one eye that focuses properly. This is known as amblyopia or "lazy eye" and is caused by the eyes sending two different images to the brain, which can happen when a child has strabismus (a squint) or is more nearsighted or farsighted in one eye than the other. The brain then ends up preferring the information coming from the stronger eye and neglecting the other.
The severity of amblyopia largely determines the kind of treatment needed. The standard treatment options are:
- Glasses to correct refractive errors (nearsightedness or farsightedness, distorted vision). Glasses may not correct it all the way to 20/20. With amblyopia, the brain is “used to” seeing a blurry image and it cannot interpret the clear image that the glasses produce. With time, however, the brain may “re-learn” how to see and the vision may increase. Remember, glasses alone do not increase the vision all the way to 20/20, as the brain is used to seeing blurry with that eye. For that reason, the normal eye is treated (with patching or eyedrops) to make the amblyopic (weak) eye stronger.
- Eye patching (occlusion therapy): The stronger eye is covered with an eye patch for several hours a day. Children who wear glasses can fit the patch over one of the lenses. This is done to encourage the weaker eye to work harder so that vision improves.
- Drug therapy: Eye drops containing atropine or a similar drug are used to temporarily blur vision in the "good" eye. They relax the muscles in the eye so that the lens will not focus for a few hours.
 |
| child wearing an eyepatch |
Children will usually first wear glasses for several weeks and then also use an eye patch. Treatment typically takes a few months, during which regular eye tests are done. Children who have refractive errors will need to keep wearing glasses in order to see clearly after treatment is completed.
If amblyopia is caused by another problem, such as a cataract, then treatment starts there. Children with severe strabismus sometimes need surgery. This kind of surgery involves tightening or relaxing the eye muscles to correct the misalignment of the eyes so that they move parallel to each other again, as far as possible. The aim is to improve spatial vision and make the condition less obvious. This surgery generally does not have anything to do with treatment for amblyopia. Sometimes amblyopia gets better without treatment, but it is not clear how often that happens.
For a long time it was widely believed that treatment is only successful if it is started early. But a comparison of two small studies involving children between the ages of 7 and 17 showed that later treatment also has a good chance of improving eyesight. Vision problems can worsen and may become permanent if amblyopia is left untreated.
Researchers from the Cochrane Collaboration – an international network of researchers – analyzed studies testing different treatments for amblyopia. They found hardly any research on treatments for amblyopia caused by strabismus. Still, there was some evidence that wearing glasses and an eye patch is more effective in improving children's vision than wearing glasses alone.
Wearing an eye patch with glasses has been shown to improve vision in children who have one amblyopic ("lazy") eye and whose eyes have different refractive powers. Generally speaking, they only need to wear the eye patch for two to six hours a day, depending on how poor their eyesight is. Sometimes wearing glasses is enough and no eye patch is needed.
Two studies compared eye patches with drug therapy, where eye drops are used once a day to numb the muscles of the healthy eye. This keeps the lens from focusing for a while. The studies showed that both treatments had similar effects.
Some people worry that patching could make the healthy eye weaker, because it is used less during the treatment. But the studies that tested eye patching treatment for amblyopia did not confirm that. Eye patches can irritate some children's skin, however.
Eye drops can have side effects like light sensitivity or stinging. This treatment may affect vision in the stronger eye for some time, but this was only temporary in the studies. Eye drops may be an option for children who find it difficult to wear an eye patch.
Children are sometimes encouraged to exercise the weaker eye by doing arts and crafts activities while wearing the eye patch. But two studies showed that this does not cause improved vision in most children. It cannot be ruled out that children who have a very "lazy" eye might benefit from that kind of exercise.
Many different factors will influence how successful the treatment is, and it is difficult to predict how things will turn out in an individual case. The child's age, the time of treatment and the type and severity of the amblyopia can all influence the results. It can take quite a long time until treatment shows some benefit, and that can be very frustrating for the child and their parents.
Most children do not have any problems wearing their eye patch in their day-to-day life. But some have a hard time wearing it as much as they are supposed to. There are several reasons for this. When their “good” eye is covered up they can only see with their weaker eye, so their vision will be worse, which can cause problems when they are playing or doing school work. Other children might tease them about the eye patch in kindergarten or at school.
Children who have to wear their eye patch for a longer time may feel more self-conscious than children who only have to wear it for a few hours a day. The doctor can let you know how many hours a day your child needs to have the patch on for it to be effective. Parents use different strategies to try to help their child cope with a patch. Some make sure their child understands why the patch is important, while others might carefully explain the results of eye tests to show that the eye is really getting stronger.
Children like to know that they are "normal." Some parents have reported that doing things like putting eye patches on toys – or even wearing patches themselves – helps make their child's eye patch feel "normal." Some parents find it helpful to also use praise or small gifts to encourage their child to wear the patch, while others think it is better to not make that big a deal out of it.
Children might not like how the patches look or think they are uninteresting. Some like covering up their glasses with something more interesting that they can pick out. Following a regular daily routine that involves wearing the patch can be important to children too, and the good news is that in a few months' time the patch will most likely be history.
Sources: Institute for Quality and Efficiency in Health Care / American Association for Pediatric Ophthalmology and Strabismus / National Eye Institute