CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0357/03573.txt

Text File | 1994-01-17 | 14.3 KB | 335 lines

$Unique_ID{BRK03573}
$Pretitle{}
$Title{Cataracts}
$Subject{Cataracts Opacities of the Lens Lens Opacities Anterior Polar
Cataract Atopic Cataract Complicated Cataract Congenital Cataract Coronary
Cataract Diabetic Cataract Electric Cataract Heat Ray Cataract Irradiation
Cataract Punctate Cataract, also known as Berulean Cataract and Blue Dot
Cataract Secondary Cataract, also known as After-cataract Toxic Cataract
Traumatic Cataract Zonular Cataract, also known as Lamellar Cataract and
Perinuclear Cataract}
$Volume{}
$Log{}

Copyright (C) 1988, 1989 National Organization for Rare Disorders, Inc.

448:
Cataracts

** IMPORTANT **
It is possible the main title of the article (Cataracts) is not the name
you expected.  Please check the SYNONYMS listing on the next page to find
alternate names and disorder subdivisions covered by this article.

Synonyms

     Opacities of the Lens
     Lens Opacities

There are many different types of Cataracts.  This entry contains
information on the following specific Cataracts:

     Anterior Polar Cataract
     Atopic Cataract
     Complicated Cataract
     Congenital Cataract
     Coronary Cataract
     Diabetic Cataract
     Electric Cataract
     Heat Ray Cataract
     Irradiation Cataract
     Punctate Cataract, also known as Berulean Cataract and Blue Dot Cataract
     Secondary Cataract, also known as After-cataract
     Toxic Cataract
     Traumatic Cataract
     Zonular Cataract, also known as Lamellar Cataract and Perinuclear
     Cataract

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.

Cataracts are abnormalities in the lens of the eye which cause a loss of
transparency (opacity).  They can occur either in one or in both eyes, and
are quite common in the elderly.  Congenital cataracts affect babies or young
children and are considered to be a rare birth defect.  Cataracts tend to
cause cloudy vision, and in many cases may result in blindness when left
untreated.

Symptoms

There are many types of Cataracts:
ANTERIOR POLAR CATARACT (including ANTERIOR PYRAMIDAL CATARACT) is a
hereditary disorder occurring in children, and characterized by lesions with
small white milky plaques in the front of the lens.  Complete loss of vision
rarely occurs, but cloudy vision and nearsightedness (myopia) are common.

ATOPIC CATARACT is characterized by variable loss of vision.  It is an
allergic disorder associated with chronic eczema and asthma.  Opacity of the
eye's lens occurs, causing decreased sharpness of vision.

COMPLICATED CATARACT is characterized by gradual blindness and severe
nearsightedness (myopia).  This disorder may be caused by a lesion inside the
eye, by disease of the vascular middle coat of the eye (uvea), or other
degeneration of the lens.  A rosette-shaped opacity may be seen in the
central part of the lens.

CONGENITAL CATARACT is a vision disorder present at birth.  It is
characterized by a loss of transparency (opacity) of the lenses, usually in
both eyes.  The white opacity may be generalized or there may be a few spots
that may vary in form and location.  The spots may occur either at the center
or at opposite ends of the eye's lens.  Impaired vision usually corresponds
to these spots.

CORONARY CATARACT is a common visual disorder occurring in adults, that
usually does not impair vision.  Zones of small opacities may occur, varying
in color from gray to brown, yellow, red or blue.  The opacities are arranged
radially in the outer layers of the lens, leaving the center of the eye
clear.

DIABETIC CATARACT is characterized by varying degrees of vision
impairment, occurring mainly in young persons with poorly controlled
diabetes.  A cloud of opacities in the eye's lens resembles a snowflake.  The
lens rapidly acquires a uniform milky white color.  The first stage of the
disorder is reversible with treatment.

ELECTRIC CATARACT is caused in a person struck by lightning or an
electric shock from high voltage electric current.  It is characterized by
variable impairment of vision.  Dotted opacities in the both lens start at
the edges and progress toward the center.

HEAT RAY CATARACT is caused by prolonged exposure of the eyes to high
temperatures and absorption of heat by the pigment of the iris.  The disorder
is characterized by varied loss of sharp vision, caused by opacity of the
disk in the rear center region of the lens.  This area is surrounded by
gradually developing, smaller opacities.

IRRADIATION CATARACT is caused by prolonged exposure to radioactivity or
X-rays.  It is characterized by varying loss of sharp vision which is related
to the degree and location of the opacity.

PUNCTATE CATARACT (CERULEAN CATARACT; BLUE DOT CATARACT) is a hereditary
opacity of the eye's lens that is often associated with Coronary Cataract.
Light or bright blue dot shaped opacities are irregularly scattered
throughout the lens.  Vision is usually normal.  This type of Cataract may
develop into Senile Cataract.

SECONDARY CATARACT (AFTER-CATARACT) may follow the extraction of a
cataract from the sac around the lens (capsule), when this capsule is torn or
cut during surgery and lens fibers remain entrapped.  Secondary Cataracts
cause blurred vision.

TOXIC CATARACT is an opacity of the eye's lens caused by toxic
substances.  Loss of clear vision varies with the degree and the location of
the opacity.  These types of cataracts usually occur in both eyes.  Fine
opacities may be mixed with iridescent crystals causing swelling, which may
produce a dull gray opacity of the eye.

TRAUMATIC CATARACT is an opacity of the lens caused by a perforating
wound of the capsule around the eye's lens.  A contusion or a foreign body
lodged in this capsule may also cause this type of cataract.  Vision
impairment varies with the severity and location of the damage.  In children,
the opacity may gradually dissolve without treatment.  In adults, secondary
glaucoma or detachment of the retina may follow appearance of the cataract.

ZONULAR CATARACT (LAMELLAR CATARACT; PERINUCLEAR CATARACT) is the most
common cataract in children.  It may be inherited through dominant genes, or
caused by malnutrition during pregnancy or early infancy.  This type of
cataract occurs in both eyes, shortly before or after birth.  The opacity is
sharply delineated, and usually consists of two opaque rings.  Partial
blindness may possibly occur.

Causes

Cataracts may have many different causes.  Some are genetic and others are
because of injury, other diseases, or for unknown reasons.

ANTERIOR POLAR CATARACT is inherited through dominant genes and it is
possibly sex-linked.

The cause of ATOPIC CATARACT is not known.  The disorder is associated
with allergies including chronic eczema and asthma.

COMPLICATED CATARACT is caused by a lesion inside the eye, associated
with disease of the middle coat of the eye, containing the iris (uvea).

CONGENITAL CATARACT may be inherited through recessive genes, or caused
by rubella contracted by a baby's mother during pregnancy.  The toxic effects
of certain drugs taken during pregnancy may also cause this disorder.

CORONARY CATARACT may be caused by an abnormality in fetal development.
In some cases, it may be genetic, and sometimes it can be caused by maternal
illness during pregnancy.

DIABETIC CATARACTS are caused by the underlying Diabetes.  (For more
information on this disorder, choose "Insulin-Dependent Diabetes" as your
search term in the Rare Disease Database and see the section on Diabetes in
the Prevalent Health Conditions/Concerns area of NORD Services.)

ELECTRIC CATARACTs are caused by exposure to excessive electric voltage.

HEAT RAY CATARACT is caused by prolonged exposure of the eyes to high
temperatures as in glass-blowing or iron-puddling, when the excessive heat is
absorbed by the pigment of the iris.

IRRADIATION CATARACT is caused by prolonged exposure of the eye to
radiation.

PUNCTATE CATARACT is possibly inherited through dominant genes.  It is
often associated with Coronary Cataract.

SECONDARY CATARACT may follow the surgical extraction of a cataract from
the lens' capsule.

TOXIC CATARACT is caused by inhalation or swallowing of chemicals or
drugs such as naphthalene dinitrophenol, triparanol, phenothiazines, ergot,
or prolonged high doses of adrenal corticosteroids.

TRAUMATIC CATARACT is caused by a perforating wound of the capsule around
the lens, by a contusion of the eyeball which ruptures the capsule, or by a
foreign object being introduced into the capsule.

ZONULAR CATARACT is either inherited through dominant genes, or possibly
caused by malnutrition during late pregnancy or early infancy.  It is
commonly associated with Rickets and defective enamel of the teeth.  (For
more information, choose "rickets" as your search term in the Rare Disease
Database.)

Causes

Human traits including the classic genetic diseases, are the product of
the interaction of two genes for that condition, one received from the father
and one from the mother.

In recessive disorders, the condition does not appear unless a person
inherits the same defective gene from each parent.  If one receives one
normal gene and one gene for the disease, the person will be a carrier for
the disease, but usually will show no symptoms.  The risk of transmitting the
disease to the children of a couple, both of whom are carriers for a
recessive disorder, is twenty-five percent.  Fifty percent of their children
will be carriers, but healthy as described above.  Twenty-five percent of
their children will receive both normal genes, one from each parent and will
be genetically normal.)

X-linked recessive disorders are conditions which are coded on the X
chromosome.  Females have two X chromosomes, but males have one X chromosome
and one Y chromosome.  Therefore in females, disease traits on the X
chromosome can be masked by the normal gene on the other X chromosome.  Since
males have only one X chromosome, if they inherit a gene for a disease
present on the X, it will be expressed.  Men with X-linked disorders transmit
the gene to all their daughters, who are carriers, but never to their sons.
Women who are carriers of an X-linked disorder have a fifty percent risk of
transmitting the carrier condition to their daughters, and a fifty percent
risk of transmitting the disease to their sons.)

In dominant disorders, a single copy of the disease gene (received from
either the mother or father) will be expressed "dominating" the normal gene
and resulting in appearance of the disease.  The risk of transmitting the
disorder from affected parent to offspring is 50% for each pregnancy
regardless of the sex of the resulting child.)

In X-linked dominant disorders the female with only one X chromosome
affected will develop the disease.  However the affected male always has a
more severe condition.  Sometimes affected males die before birth so that
only female patients survive.

Therapies:  Standard

Surgery is used to remove some types of Cataracts.  The lens is removed and
may be replaced with an implant.  A patch is worn temporarily.  Contact
lenses may help improve sharpness of vision.  During recent years lasers have
been used increasingly to remove cataracts.  Laser techniques are used to
loosen either the cornea, the lens capsule, or other material when they are
adhering to the lens.  It is often possible to remove cataracts at outpatient
clinics since the procedure may take only a few hours.

Therapies:  Investigational

After removal of the affected lens in children with Congenital Cataract an
intraocular lens (IOL) has been implanted.  If technically feasible, the IOL
is implanted in the lens capsule.  More research is needed before this
implantation can be used more generally to preserve vision and reduce double
vision.

This disease entry is based upon medical information available through
June 1988.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Cataracts, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     PACK (Parents of Cataract Kids)
     179 Hunters Lane
     Devon, PA  19333
     [phone]
     [phone]

     NIH/National Eye Institute
     9000 Rockville Pike
     Bethesda, MD  20892
     [phone]

     International Institute for Visually Impaired, 0-7, Inc.
     1975 Rutgers
     East Lansing, MI  48823
     [phone]

     The National Association for Parents of the Visually Impaired, Inc.
     P.O. Box 180806
     Austin, TX  78718
     [phone]

     National Association for Visually Handicapped
     305 East 24th Street, Room 17-C
     New York, NY  10010
     [phone]

     Vision Foundation
     818 Mt. Auburn Street
     Watertown, MA  02172
     [phone]
     [phone] (within MA)

For genetic information and genetic counseling referrals, please contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

References

DIAGNOSIS AND MANAGEMENT OF CATARACTS IN INFANCY AND CHILDHOOD:  L.B.
Nelson;  Ophthalmic Surg (August 1984:  issue 15(8)).  Pp. 688-697.

GRATING ACUITY DEVELOPMENT AFTER EARLY SURGERY FOR CONGENITAL UNILATERAL
CATARACT:  E.E. Birch, et al.; Archives Ophthalmol (December 1986:  issue
104(12)).  Pp. 1783-1787.

PHTHISIS BULBI AFTER INTRAOCULAR LENS IMPLANTATION IN A CHILD:  S.C.
Gieser, et al.; Canadian Journal Ophthalmol (August 1985:  issue 20(5)).  Pp.
184-185.

PRINCIPLES OF NEUROLOGY, 4th ed., R. Adams and Maurice Victor, McGraw-
Hill, New York, 1989, P. 1148.