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What is a cataract?
A cataract is the
clouding of the eye’s normally clear lens. The lens is located
directly behind the iris (the colored part of the eye). The lens’ job
is to help focus the light on the retina (the light sensitive tissue
on the back of the eye). A cloudy lens prevents light rays from
reaching the retina and results in hazy, or blurry, vision. The degree
of visual impairment caused by a cataract varies and depends on how
much of the lens is affected by the cataract.
What causes cataracts
in children?
Although most cataracts
occur in adults as part of the aging process, infants and children can
also be affected. Occasionally infants are even born with a cataract.
Although infant cataracts may be inherited or occur as part of certain
infections, such as German measles (rubella) it is usually impossible
to determine the exact cause. Certain blood and urine tests may be
performed to evaluate some of the known causes; most often they are
negative.
A cataract may develop
later in childhood often as a result of eye injury or a disease
process involving other parts of the body. Other causes include
abnormal lens growth or the late appearance of inherited cataracts.
How are cataracts
treated?
Some childhood
cataracts that involve only part of the lens may not interfere with
vision. These small cataracts usually do not require treatment but
should be observed periodically. Moderate size cataracts that do
interfere with vision may require treatment with glasses with
treatment for amblyopia (“lazy” eye). Larger cataracts which severely
affect the vision require immediate surgery.
Using very special
microsurgical techniques an ophthalmologist removes the entire lens.
All cataract operations require incisions into the eye. In children,
this surgery is performed under general anesthesia. LASERS CANNOT
REMOVE CATARACTS!
How is vision corrected
after surgery?
Once the cloudy lens is
removed, the child will need a substitute lens to focus images on the
retina. This can be done with glasses, contacts lenses or intraocular
lenses. The decision on regarding the type of visual correction is
personalized for each case. It is a decision that you and your
ophthalmologist will make together. REGARDLESS OF THE METHOD THE CHILD
WILL ALWAYS NEED BIFOCAL GLASSES TO SEE NEAR OBJECTS CLEARLY.
Glasses work well for
children who have had cataracts removed from both eyes. They cannot be
used if the cataract has been removed from one eye only, due to the
difference in magnification that would result between to two eyes. The
child would see one magnified image (on the side that had the cataract
surgery) and one normal image, resulting in double vision. The child’s
brain would correct for this by “turning off” (suppressing) the image
from the operated eye. This results in amblyopia, or “lazy” eye. (See
below.)
Contact lenses are used
when the surgery is performed in one or two eyes. Usually, special
high powered lenses made of silicone are used. The exact type of lens
used for each patient is determined on an individual basis. This fit
takes into account the shape, and length of the eye as well as the
patient, of parent’s dexterity. Since an infant’s eye grows rapidly,
frequent lens changes may be necessary.
One of the newest ways
of correcting the focusing power in infants with cataracts is by using
an artificial implant in the same way that they are used for adults.
However unlike adults, in children it is often difficult to predict
what power intraocular lens will be needed as the child’s eye is still
growing. The growth of the eye will affect the power needed for clear
focusing. If an intraocular lens is placed, the surgeon(s) will pick a
power based on the length and curvature of the eye(s) as well as by
using their expertise in this field and best judgment. If an
intraocular lens is placed, depending on the condition of the eye(s)
and child’s age, it could require removal in the future because of
lens power modifications, problems with scarring, displacement, or
inflammation. All of the above mentioned treatments as well as
glasses, eye patches, eye drops, and additional surgeries may be
needed.
Amblyopia
Poor vision resulting
from amblyopia or “lazy” eye can be caused by a cataract. While the
visual system is developing, the brain must receive clear images to
both eyes. If this does not occur, the visual part of the brain for
that eye will not develop properly. For this reason, when a cataract
develops in infancy surgery should be performed as soon as vision is
threatened.
When amblyopia is
present, cataract removal is only the first step in treatment. Proper
optical correction is necessary and intensive patching regimens will
be likely. Even with prompt and aggressive treatment, some children
develop only partial visual recovery.
Please see our
additional section on cataract surgery
for more information.
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