Amblyopia, also known as lazy eye, is a vision development disorder in which an eye fails to achieve normal visual acuity, even with prescription eyeglasses or contact lenses. We asked Dr Claire Cullen, an ophthalmologist specialising in paediatric eye conditions and adult strabismus, to explain the different types of lazy eye, causes and the treatment options.
Normal vision develops during the first few years of life. At birth, infants have very poor vision, however as they use their eyes their vision improves because the vision centres in the brain are developing. If an infant is not able to use their eyes for various reasons, the vision centres do not develop properly and the vision is decreased despite the normal appearance of the structures of the eyes.
In most cases, only one eye is affected by amblyopia or lazy eye. But in some cases, reduced visual acuity can occur in both eyes. Amblyopia is the leading cause of vision loss amongst children. It is important that it is detected early in life and promptly treated to optimise the child’s chances of a successful outcome. If it is left untreated, lazy eye can cause severe visual disability in the affected eye, including legal blindness.
Signs and symptoms of amblyopia (lazy eye) in children
Because amblyopia typically starts in infancy, when vision is developing rapidly, symptoms of the condition can be difficult to discern. Some forms of amblyopia, such as that associated with a large angle strabismus, may be easily detected by parents. Other types of amblyopia e.g. a high refractive error might cause a child to move very close to objects or squint his or her eyes.
Still other forms of amblyopia may NOT be obvious to parents and therefore must be detected by Vision Screening. It is important to have your child’s eyes examined as recommended to make sure he or she has normal vision in both eyes and that the eyes function together properly as a team.
What causes amblyopia (lazy eye) in children?
There are three types of amblyopia and each has a different cause:
This occurs when the eyes are not aligned and the brain begins to ignore, or “turn off” the eye that is not straight. This leads to amblyopia in that eye. Strabismus is the most common cause of amblyopia.
This is also known as anisometropic amblyopia. It occurs when there is a large or unequal difference in strength (refraction) between the two eyes. The brain relies on the eye that has less need for glasses and “tunes out” the blurred vision from the other eye, causing amblyopia in that eye from disuse.
This type of amblyopia can affect one or both eyes and may be “invisible” because the child does not complain of blurry vision. The amblyopic eye may also not look any different from the normal seeing eye, and therefore, parents and paediatricians may not think there is a problem. For these reasons, this kind of amblyopia may not be found until the child has a vision test.
This type of amblyopia is caused by something that obstructs light from entering and being focused in a baby’s eye. Examples include congenital cataracts, corneal scars, ptosis etc. Prompt treatment of the cause is necessary to allow normal visual development to occur.
When should amblyopia (lazy eye) in children be treated?
Amblyopia should always be addressed and treated as early as possible. If necessary, children with significant refractive errors (nearsightedness, farsightedness or astigmatism) can wear glasses or contact lenses when they are as young as a few weeks of age.
Other conditions that could cause amblyopia such as cataracts are usually treated promptly in order to minimise the development of amblyopia.
How old is too old for amblyopia (lazy eye) treatment in a child?
A study by the National Institutes of Health (NIH) confirmed that some improvement in vision can be attained with amblyopia therapy initiated in younger teenagers (through age 14 years), however better treatment success is achieved when treatment starts at an early age.
What is the goal of lazy eye treatment?
In all cases, the goal is the best possible vision in each eye. While not every child will improve to 20/20, most can obtain a substantial improvement in vision. The earlier the treatment for amblyopia, the more successful the treatment tends to be.
What will happen if lazy eye is not treated?
If amblyopia is not treated the vision in the affected eye/s will be permanently decreased causing deficits in depth perception and peripheral vision. Moreover if the good eye becomes injured or affected by a disease, significant lifetime disability may result.
How is lazy eye treated?
In some cases of refractive amblyopia, normal vision can be achieved simply by fully correcting the refractive errors in both eyes with glasses or contact lenses.
Usually, however, at least some patching of the “good” eye is needed to force the brain to pay attention to the visual input from the amblyopic eye and enable normal visual development to occur in that eye. Other mainstays of amblyopia treatment are addressing the cause e.g. removal of cataracts to allow a clear image to enter the eye.
What is eye patching?
Eye patching is a treatment for amblyopia where the strong eye is occluded (closed) by an adhesive patch to force the weaker eye to see. The treatment can work very well when patching instructions are carefully followed. The best time to use eye patching to correct amblyopia is during early childhood (the earlier the better).
Why does my child need to wear an eye patch?
Patching the good eye forces the use of the weak eye and encourages the development of better vision. Glasses may also be prescribed to treat any focusing problems, but patching may still be required to treat the lazy eye.
What kind of eye patch should my child use?
The best kind of eye patch is an orthoptic patch with adhesive on the back (similar to a plaster). You should put the patch directly on your child’s skin around his/her strong eye.
Some children are sensitive to the adhesive so, if your child has this problem, you can try a few things including:
- Make sure you are not leaving the patch on overnight.
- Use a warm facecloth or sponge to wet the patch before removing it.
- Switch to a different brand of adhesive patch.
- Cut various holes or sections from the adhesive portion of the patch. Ensure the patch remains secure and doesn’t allow peeking.
- Try ‘pre-sticking’ the patch to clothing or your arm to reduce the amount of adhesive before applying.
- Apply a thin layer of ‘milk of magnesia’ to the area of skin to which the patch is applied. Let it dry and then attach the patch to this area. This will protect the skin and enable the patch to come off easily.
- If all else fails; you can try an alternative form of patch rather than the adhesive type.
Another type of patch is made of material. This can be used over glasses but in order for this type of patch to work well the glasses should fit tightly and the cloth should not have any holes.
How long will my child need to wear an eye patch for?
The amount of patching therapy required is different for each child. Your child’s vision may improve a few weeks after starting patching but it may take many months for the best results. There are many factors that can influence the amount of treatment needed. Some of these include:
- Age. In general the younger the child and the earlier treatment is started, the less time it should take to improve vision.
- Severity. Some types of amblyopia are more difficult to treat than others. Your doctor or therapist will prescribe either full-time or part-time patching of the stronger eye during the day. Once vision has improved or stabilised, patching will be tapered slowly to prevent relapse. Sometimes the vision in the weaker eye can deteriorate and the amount of patching may need to increase again, because of this it is important to have your child’s vision checked on a regular basis.
Unfortunately not all children’s vision will improve with patching. After a reasonable period of compliant patching, it may be advised by your doctor to stop patching.
When should my child wear an eye patch?
Your child should wear the patch during the daytime when he/she is awake. There is no particular activity that will improve the vision more than another activity. The most important part of treatment is keeping the patch on for the prescribed treatment time.
Some eye doctors believe that the performance of near activities (reading, colouring, hand-held computer games) during treatment may be more stimulating to the brain and produce better or more rapid recovery of vision.
Should eye patching be done during school hours?
There are often questions about whether children should patch at school or at home: this should be decided on an individual basis. In many instances, school is an excellent time to patch, taking advantage of a non-parental authority figure. Patching during school hours also gives the class an opportunity to learn valuable lessons about accepting differences between children.
If the patient, teacher, and classmates are educated appropriately, school patching need not be a socially stigmatising experience. On the other hand, frequently a parental or other family figure may be more vigilant in monitoring patching than is possible in the school setting. Parents should be flexible in choosing when to schedule patching.
What if my child won’t keep the eye patch on?
The ophthalmologist will give the instructions and monitor the progress but the patient and the family will need do the hard work of actually performing the treatment. Children do not like to have their good eye patched, especially if the vision in the amblyopic eye is very low, but parents must stand by them and help them do what’s best.
Parents play probably the most important role in a successful treatment. It is very common for children to refuse to wear an eye patch. Successful treatment mostly depends on your commitment, involvement and ability to gain your child’s cooperation.
Remember that it does get easier so don’t give up too soon! It may take a lot of encouragement from family, friends and teachers for your child not to remove the patch. If your child does not want to wear their eye patch, try these tips:
- Consider rewarding your child if he/she keeps the patch on for the full amount of time.
- Let your child choose the colour and pattern of his/her eye patch.
- Try patching during your child’s favourite activities. Some kids are more willing to wear patches while they are watching TV or playing games.
- It may help to start slowly; high levels of patching early may induce frustration. Ask your doctor if you can gradually add an hour a day or week.
- Use positive reinforcement and avoid negative reinforcement or power struggles.
- Use a timer to indicate when the patch comes off.
- Consider having a rule that only parents or caregivers can touch the patch.
- More “forceful” measures can be considered if your child refuses to wear the patch, but these should be discussed with your doctor. There are occasionally times when patching continues to be impossible and you may have to accept that one eye will always be poorer than the other. It is always reassuring to know that you have done everything you possibly can with patching before accepting this.
Is there an alternative to eye patching to treat amblyopia?
Sometimes the stronger eye can be “penalised” by using eye drops such as atropine. Atropine temporally blurs the vision in the good eye and works as an alternative to patching in selected cases of mild to moderate amblyopia. Not all children benefit from eye drop treatment for amblyopia. Penalising eye drops do not work as well when the stronger eye is nearsighted or when the degree of amblyopia is severe. Atropine is also not without potential side effects.
Can you treat amblyopia (lazy eye) with surgery?
Amblyopia cannot be corrected with surgery. Surgery may be performed to straighten the eyes, and patching may still be required before and/or after surgery. Children who are born with cataracts may need surgery to take out the cataracts. After surgery, the child will usually need vision correction with glasses or contact lenses and patching.
What happens if amblyopia treatment does not work?
In some cases, treatment for amblyopia may not succeed in substantially improving vision. It is hard to decide to stop treatment, but sometimes it is best for both the child and the family. Children who have amblyopia in one eye and good vision only in their other eye can wear safety glasses and sports goggles to protect the normal eye from injury. As long as the good eye stays healthy, these children function normally in most aspects of society. In most cases, loss of vision from amblyopia can be prevented or successfully treated if started early enough and if the degree of amblyopia is not extreme.