What is amblyopia?
Amblyopia or "lazy eye" is a common vision
problem in children and is responsible for vision loss in more children
than all other causes combined. Amblyopia is decreased vision of
a child that results when one or both eyes send a blurry image to
the brain. The brain does not learn to see clearly. Amblyopia may
occur even when there is no observable structural abnormality of
the eye. If amblyopia is not treated in a timely fashion the vision
loss may be permanent into adulthood.
How is amblyopia detected?
A parent or primary care physician may notice either
poor vision or strabismus.
Primary care physicians routinely screen for amblyopia. Amblyopia
is sometimes detected on pre-school vision screening.
What are the types of amblyopia?
The types and causes of amblyopia are: Strabismic
amblyopia, deprivation amblyopia, refractive amblyopia, or a combination
of the three. All forms of amblyopia result in reduced vision in
the effected eye(s).
What is strabismic amblyopia?
Strabismic amblyopia develops when the eyes are not
aligned. When an eye turns in, out, up or down the brain may "turn off" the
eye that is not aligned and the vision subsequently decreases.
What is deprivation amblyopia?
Deprivation amblyopia develops when a cataract or
similar condition "deprives" a
child's eye of visual input. If not treated very early, vision loss
may be severe and may affect both eyes.
What is refractive amblyopia?
Refractive amblyopia occurs when a child has a large
or unequal amount of refractive error (need for glasses). Usually
the brain "turns
off" the eye that has the larger refractive error. Parents and
primary care physicians may not notice a problem because the eyes
are often aligned and the good eye vision is normal. Therefore, this
kind of amblyopia may not be detected unless the vision is tested.
Will glasses help a child with refractive amblyopia
see better?
Sometimes, but glasses alone may not correct the vision
to 20/20. Glasses are prescribed initially and vision monitored
until there is no further improvement. Any remaining amblyopia is
then treated.
Can both eyes have amblyopia?
Yes. When there are equal amounts of high refractive
error, both eyes may have poor vision (bilateral amblyopia) even
when wearing glasses. Constant wear of glasses is very important
and vision is checked frequently. Vision typically improves but may
take several years.
When and how is amblyopia treated?
Amblyopia is treated during childhood and the earlier
the age the better the treatment result. Usually, by the age of 9-10
years, the visual system is stable and the vision does not improve
much with treatment. However, vision improvement can occur up to
17 years in some cases.
The underlying cause of the amblyopia is treated
(correction of refractive error with glasses or contact lenses, removal
of cataract, etc) and then vision reassessed. If vision is still
reduced, consideration is given to amblyopia treatment. The main
forms of treatment are patches and drops. Occlusion treatment involves
patching the better seeing eye to stimulate vision in the poorer
seeing eye. The ophthalmologist prescribes the hours per day to patch
based on the age of the child and the severity of vision deficit.
Follow up exams assess vision in the poorer seeing eye for improvement
and in the better seeing eye to confirm no decrease in vision (occlusion
amblyopia). In addition to an ophthalmologist, an orthoptist may
be involved in the assessment and management of amblyopia. Orthoptists
are allied health professionals who specialize in amblyopia and
strabismus.
What kind of patch should be used?
The classic patch is an adhesive "Band-Aid" type
which is applied directly to the skin around the eye. These are available
in different sizes for younger and older children. For children wearing
glasses, a semi-transparent sticker (Bangerter filter) placed on
the lens or a cloth patched slipped onto the glasses may be utilized. "Pirate" patches
on elastic bands are not recommended due to easy removal by children.
Are any specific activities recommended while patching?
No. However, performance of near activities (reading,
coloring, hand-held computer games) while patching may be more stimulating
to the brain and produce a quicker recovery of vision. Watching a
favorite TV program or use of a computer while patching sometimes
encourages compliance. Sometimes patching may be utilized at school.
What
if a child refuses to wear the patch?
Many children resist wearing a patch at first. Successful
patching requires persistence and much encouragement from family
members, neighbors, teachers, etc. Children often throw a temper-tantrum,
but eventually learn not to remove the patch. A reward to the child
for successful patching can be helpful. Usually co-operation improves
as the vision improves.
Is there an alternative to patching to treat amblyopia?
Sometimes the stronger eye can be "penalized" or
the vision blurred to below the level of the poorer seeing eye. This
can be done by using an eye drop (Atropine) in the better seeing
eye and possibly changing the glasses prescription. Ophthalmologists
sometimes use this treatment for mild and moderate degrees of amblyopia.
Penalizing eye drops work less well when the good eye is nearsighted.
What are appropriate goals of amblyopia treatment?
In all cases, the goal is the best possible vision
in each eye. While not every child can be improved to 20/20, most
can obtain a substantial improvement in vision. Realistic goals depend
on the age of the child and the level of vision when the amblyopia
is diagnosed. Your ophthalmologist can give you an estimate of vision
potential.
How long does amblyopia treatment last?
Vision usually improves within a few weeks but optimal
results may take several months and depends on the level of vision
and age. Once vision has been maximized, maintenance treatment until
9-10 years of age may be required to keep the vision from regressing.
What happens if amblyopia treatment does not work?
In some cases, treatment for amblyopia may not succeed
in substantially improving vision. It is a difficult decision to
discontinue treatment, but sometimes that is best for both the child
and family. Children who have significant amblyopia in one eye should
utilize protective eyewear to protect the better seeing eye from
injury. As long as the better seeing eye remains healthy, normal
daily function is expected.
Can surgery be performed to treat amblyopia?
No.
Where can I learn more about amblyopia research?
More information about past and ongoing clinical studies
regarding amblyopia can be found at the National Eye Institute web
site:
www.nei.nih.gov/health/amblyopia/index.asp.
Source: www.aapos.org/
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