What is amblyopia?
The eyes of very young children will not develop correctly unless vision is aligned, balanced and focused. Sometimes, the vision in one eye is much worse than the vision in the other eye. When this happens, the brain will start to "ignore" the eye with worse vision. This actually makes the vision in that eye even worse. This condition is called amblyopia.
Amblyopia is a dangerous condition. If it is not treated, an eye with amblyopia eventually will develop severely diminished vision.
Why do children get amblyopia?
Some children cannot see well in one eye because there is something that blocks light from getting through. It could be that the eye's lens, which is supposed to be clear, has become cloudy. This is called a cataract. In some children's eyes, a small amount of blood or other material in the back of the eye is blocking vision.
More often, however, amblyopia happens because one eye has much better focus than the other. For example, one eye might be very nearsighted. Objects that are far away will look very blurry to this eye. If the other eye is not nearsighted, the same far-away objects will be focused clearly by that eye.
With a condition like amblyopia, the brain cannot put the blurry image and the clear image together in the way that we usually see. Instead, the brain will start to ignore the blurry image. If this goes, the vision in the eye that sees the blurry image will start to deteriorate. With amblyopia, not only will the image be blurry, it will get very dim. The eye can also stop moving normally, and it might stay turned away to the side. This is why amblyopia is sometimes called "lazy eye."
Sometimes there is a problem with the muscles that move the eye. This problem, called strabismus, prevents the two eyes from moving together in the usual way. This can cause double vision. In order to avoid this double vision, the brain might start to ignore the image from one eye. This will eventually cause the vision in that eye to deteriorate. (For more information, see the "Strabismus" fact sheet from the Cole Eye Institute.)
The important thing to remember is that amblyopia often starts before there is any obvious sign that something is wrong. This is why babies and young children need to have their eyes checked at regularly scheduled appointments with the doctor.
When should babies and young children have eye examinations?
The American Academy of Ophthalmology recommends that children have eye examinations:
- Once before the child is 3 months old.
- Once between the ages of 6 months and 1 year.
- Once at about 3 years of age.
- Once at about 5 years of age.
How does the doctor know if a child has amblyopia?
Pediatricians will check to make sure that the child's eyes let light all the way through, and that the eyes are moving normally. If there seems to be something blocking the light, or if there seems to be a problem with the movement of the eyes, the pediatrician might recommend a visit to an eye specialist.
The eye doctor has special instruments that can see inside the eyes and measure how well each eye focuses. He or she can also perform special tests to make sure the eyes are moving together correctly.
If there is something blocking light from getting into the eye, it might be necessary to operate and remove the blockage. If strabismus is preventing the eyes from moving together correctly, your doctor might recommend glasses or surgery on the muscles of the eye. And if the focus of one eye is very different from the other, eyeglasses or contact lenses might be necessary.
Sometimes these problems will be found before the child gets amblyopia. In most children with amblyopia, however, vision has already started to deteriorate by the time they visit the doctor.
How is amblyopia treated?
Only a doctor can recommend the right treatment for a child with amblyopia, and that requires a careful examination.
First, any of the problems that cause amblyopia will have to be treated. After the doctor makes sure that the eye is moving correctly, is allowing light to pass through, and is in focus, the right treatment for amblyopia can be recommended.
The most common treatment for amblyopia is to force the brain to start using the affected eye with amblyopia by putting a patch over the "good" eye. At first, the child will have a hard time seeing with just the weaker eye. It is very important to keep using the patch, however, because this will force the eye with amblyopia to "work harder." Eventually, the vision in the eye with amblyopia will get better. This could take weeks, months, or even years. But if the child keeps using only the eye with amblyopia, the vision will continue to improve. After the doctor determines that the vision is back to normal, the patch may not be needed again.
For some children with mild amblyopia, the doctor might recommend using an eye drop called atropine in the "good" eye instead of a patch. Atropine makes it impossible for that eye to focus close-up. This forces the eye with amblyopia to do most of the work while the child is playing with toys, eating, drawing, reading and so on. This can also improve the vision in the eye with amblyopia.
Your doctor will be able to tell you what amblyopia treatment is right for your child.
How successful is treatment to correct amblyopia?
When other eye problems are treated, and the treatment for amblyopia is started early enough, most children will regain normal vision.
In order for treatment to be successful, however, it must be started as soon as possible. Amblyopia becomes much more difficult to treat after about 6 years of age. And if there is too much vision lost in the eye with amblyopia, it might be impossible to get it all back.
It is also important to follow all of your doctor's advice about treatment. This can be very difficult, because many children do not want to wear an eye patch every day. But if the child is allowed to take the eye patch off, he or she will resume using only the "good" eye to see.
Amblyopia can be very worrisome for parents. There are several groups that offer advice and support. The not-for-profit group Prevent Blindness America, for example, has created the Eye Patch Club. Telephone: (800) 331-2020. Web site: www.preventblindness.org.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition.
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