Congenital Cataracts
What is a cataract?
A cataract is any cloudiness or opacity of the normally
clear lens of the eye. Cataract size ranges from very small to entire
lens involvement.
How common are infantile and childhood cataract?
About 3 children per 10,000 children have a cataract.
The incidence is variable throughout the world.
How does a cataract
cause vision loss?
A cataract causes decreased vision by interfering
with the light ray path to the retina (back part of the eye). Abnormal
vision development resulting in a lazy eye (amblyopia) can occur
when a child has a cataract.
Why are
some babies born with a cataract?
Pediatric cataracts often occur because of abnormal
lens development during gestation. Lens malformations that occur
in conjunction with other findings are often the result of a genetic
or metabolic abnormality. These cataracts may be present at birth
or develop during childhood. However, most pediatric cataracts are
not associated with other abnormalities.
Do all cataracts in babies
and children need to be removed?
No. Some cataracts are small and/or off-center in
the lens. These cataracts do not need to be removed because vision
develops normally, even if the cataract is left in place.
What types
of cataracts occur in babies and children?
The human crystalline lens consists of a center part
called the nucleus and outer part called the cortex, both contained
within a capsule. Cloudiness can occur in one or more parts of the
lens.
- A nuclear cataract is cloudiness of the center part
of the lens.
- A lamellar cataract is cloudiness between the nuclear
and cortical layers of the lens.
- A posterior subcapsular cataract
is opacity of the lens cortex adjacent to the posterior capsule
of the lens.
- An anterior polar cataract is a small, usually central
opacity of the front part of the lens capsule. This type of cataract
is often shaped like a pyramid. Anterior polar cataracts generally
do not grow during childhood and can usually be managed without
surgery.
- A posterior polar cataract is a central opacity at the
back of the lens.
- Persistent hyperplastic primary vitreous is often
associated with a cataract. During development of the eye a blood
vessel extends from the optic nerve (back of the eye) to the developing
lens to provide nutrients to the young growing lens. Failure of
this blood vessel to regress during development can cause a plaque-like
cataract on the back of the lens. The persistent stalk extending
from the back of the eye toward the cataract can cause retinal
abnormalities.
What is a traumatic cataract?
A traumatic cataract results from either a blunt or
penetrating force that damages the lens. The cataract can form shortly
after the trauma or months to years after the injury.
At what age
should a cataract be removed from an infant or child?
Cataracts that cause significant visual loss are typically
removed as soon as is safely possible. The visual part of the brain
very actively develops during infancy and childhood. If a cataract
causes a blurred picture, the visual part of the brain does not develop
normally and causes amblyopia.
A visually significant cataract should be removed and vision rehabilitated
before the brain reaches visual maturity. This often involves patching
an eye.
How is a cataract removed in infants and children?
An incision is made into the eye and an opening is
made in the front of the lens capsule. The very soft inner part of
the child's lens is suctioned out of the capsule. Younger children
may require an additional opening in the posterior lens capsule with
some vitreous gel removal. An intraocular lens is then sometimes
placed within the lens capsule. Lastly, the incisions are closed.
What
are the risks of cataract surgery in infants and children?
Cataract surgery performed by an experienced surgeon
is generally very safe. No surgical procedure is without risks, however.
The risks of pediatric cataract surgery include infection, retinal
detachment, development of glaucoma, displacement of the intraocular
lens, development of capsular cloudiness and development of vitreous
cloudiness.
How does the eye focus once the cataract is removed?
There are several methods to restore focusing ability
of the eye:
- an intraocular lens is sometimes placed in the eye at the time
of cataract removal.
- a contact lens can be placed on the surface of the
eye.
- glasses can be used to focus the light rays. Glasses are
often very thick and are generally not a good option with unilateral
cataracts.
How are contact lenses used after cataract surgery?
If an intraocular lens is not placed, a child can
wear a contact lens to focus the light rays. Contact lenses are specifically
designed for the correction of vision in infants and young children
who have had cataract surgery. These lenses are often worn for extended
periods. As the eye grows the power of the contact lens can be
updated.
Source: www.aapos.org
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