Amblyopia is poor vision in an eye that did not develop normal
sight during early childhood.
It is sometimes called "lazy eye." When one eye develops good vision while the other does
not, the eye with poorer vision is called amblyopic.
Usually, only one eye is affected by Amblyopia. The condition is common, affecting
approximately 2 or 3 out of every 100 people. The best time to correct Amblyopia is during
infancy or early childhood. Parents must be aware of this potential problem if they want to
protect their child's vision.
How Does Normal Vision Develop?
Newborn infants are able to see, but as they use their eyes during the first months of life,
vision improves. During early childhood years, the visual system changes quickly and vision
continues to develop. If a child cannot use his or her eyes normally, vision does not
develop properly and may even decrease. After the first nine years of life, the visual
system is usually fully developed and usually cannot be changed. The development of equal
vision in both eyes is necessary for normal vision. Many occupations are not open to people
who have good vision in one eye only.
If the vision in one eye should be lost later in life from an accident or illness, it is
essential that the other eye have normal vision. Without normal vision in at least one eye,
a person is visually impaired. For all of these reasons, Amblyopia must be detected and
treated as early as possible.
When Should Vision Be Tested?
It is recommended that all children have their vision checked by their pediatrician, family
physician or ophthalmologist (medical eye doctor) at or before their fourth birthday. Most
physicians test vision as part of a child's medical examination. They may refer a child to
an ophthalmologist (a medical eye doctor) if there is any sign of an eye condition. New
techniques make it possible to test vision in infants and young children. If there is a
family history of misaligned eyes, childhood cataracts or a serious eye disease, an
ophthalmologist can check vision even earlier than age three.
What Causes Amblyopia?
Amblyopia is caused by any condition that affects normal use of the eyes and visual
development. In many cases, the conditions associated with Amblyopia may be inherited.
Children in a family with a history of Amblyopia or misaligned eyes should be checked by an
ophthalmologist early in life. Amblyopia has three major causes:
- Strabismus (misaligned eyes). Amblyopia occurs most commonly with misaligned or
eyes. The crossed eye "turns off" to avoid double vision and the child uses only the
- Unequal focus (refractive error). Refractive errors are eye conditions that are
wearing glasses. Amblyopia occurs when one eye is out of focus because it is more
nearsighted, farsighted or astigmatic than the other. The unfocused (blurred) eye
off" and becomes amblyopic. The eyes can look normal but one eye has poor vision.
the most difficult type of Amblyopia to detect and requires careful measurement of
- Cloudiness in the normally clear eye tissues. An eye disease such as a cataract (a
of the eye's natural lens) may lead to Amblyopia. Any factor that prevents a clear
from being focused inside the eye can lead to the development of Amblyopia in a
is often the most severe form of Amblyopia.
How Is Amblyopia Diagnosed?
It is not easy to recognize Amblyopia. A child may not be aware of having one B eye and one
weak eye. Unless the child has a misaligned eye or other obvious abnormality, there is often
no way for parents to tell that something is wrong. Amblyopia is detected by finding a
difference in vision between the two eyes. Since it is difficult to measure vision in young
children, your ophthalmologist often estimates visual acuity by watching how well a baby
follows objects with one eye when the other eye is covered. If one eye is amblyopic and the
good eye is covered, the baby may attempt to look around the patch, try to pull it off or
Poor vision in one eye does not always mean that a child has Amblyopia. Vision can often be
improved by prescribing glasses for a child. Your ophthalmologist will also carefully
examine the interior of the eye to see if other eye diseases may be causing decreased
vision. These diseases include:
- Other disorders of the inner eye.
How Is Amblyopia Treated?
To correct Amblyopia, a child must be made to use the weak eye. This is usually done by
patching or covering the B eye, often for weeks or months. Even after vision has been
restored in the weak eye, part-time patching may be required over a period of years to
maintain the improvement. Glasses may be prescribed to correct errors in focusing. If
glasses alone do not improve vision, then patching is necessary. Occasionally, Amblyopia is
treated by blurring the vision in the good eye with special eye drops or lenses to force the
child to use the amblyopic eye.
Amblyopia is usually treated before surgery to correct misaligned eyes, and patching is
often continued after surgery as well. If your ophthalmologist finds a cataract or other
abnormality, surgery is required to correct the problem. After surgery, glasses or contact
lenses can be used to restore focusing, while patching improves vision. Amblyopia cannot be
cured by treating the cause alone. The weaker eye must be made Ber in order to see normally.
Prescribing glasses or performing surgery can correct the cause of Amblyopia, but your
ophthalmologist must also treat the Amblyopia. If Amblyopia is not treated, several problems
- The amblyopic eye may develop a serious and permanent visual defect;
- Depth perception (seeing in three dimensions) may be lost;
- If the good eye becomes diseased or injured, a lifetime of poor vision may be the result.
Your ophthalmologist can give you instructions on how to treat Amblyopia, but it is up to
you and your child to carry out this treatment. Children do not like to have their eyes
patched, especially if they have been depending on that eye to see clearly. But as a parent,
you must persude your child to do what is best for him or her. Successful treatment mostly
depends on your interest and involvement, as well as your ability to gain your child's
cooperation. In most cases, parents play an important role in determining whether their
child's Amblyopia is to be corrected.
Loss of Vision Is Preventable
Success in the treatment of Amblyopia also depends upon how severe the Amblyopia is and how
old the child is when treatment is begun. If the problem is detected and treated early,
vision can improve for most children. Sometimes part-time treatment may have to continue
until the child is about nine years of age. After this time, Amblyopia usually does not
return. If Amblyopia is first discovered after early childhood, treatment may not be
successful. Vision loss from strabismus or unequal refractive errors may be treated
successfully at a much older age than the Amblyopia caused by cloudiness in tissues in the