CONNECTIVE TISSUE
CONTACT LENSES
and may cause the eyelids to be stuck
together on waking. In allergic conjunc-
tivitis, the discharge is clear and the
eyelids are often swollen.
Bacterial infections are treated with
antibiotic
eyedrops or ointment. Viral
conjunctivitis often disappears without
treatment. Allergic conjunctivitis may
be relieved by eyedrops containing an
antihistamine
or a
corticosteroid drug
.
Other forms of conjunctivitis include
neonatal
ophthalmia
,
keratoconjunctivi-
tis
,
and
trachoma
.
connective tissue
The material that
supports, binds, or separates the vari-
ous structures of the body.
Tendon
s and
cartilage
are made up of connective tis-
sue, and it forms the matrix (ground
substance) of
bone
and the nonmuscu-
lar structures of
arteries
and
veins
.
connective tissue diseases
Types of
autoimmune disorders
that often affect
blood vessels and produce secondary
connective tissue
damage. They include
rheumatoid
arthritis
,
systemic
lupus
erythematosus
,
polyarteritis nodosa
,
scle-
roderma
, and
dermatomyositis
.
Conn's syndrome
A disorder caused
by the secretion of excessive amounts
of the hormone
aldosterone
by a non-
cancerous tumour of one of the
adrenal
glands
.
(See also
aldosteronism
.)
consciousness
A state of alertness in
which a person is fully aware of his or her
thoughts, surroundings, and intentions.
consent
The legal term describing a pa-
tient's agreement to a doctor performing
an operation, arranging drug treatment,
or carrying out diagnostic tests. Strictly,
consent is valid only if the patient has
been fully informed about the purpose of
the procedure, the likely outcome, and
any complications and side effects. Con-
sent cannot be given by children or by
people with serious mental disorders,
but a relative may give or withhold con-
sent on their behalf. The patient's
consent is also needed before a doctor
supplies confidential information to an
insurance company, employer, or lawyer.
constipation
The infrequent or difficult
passing of hard, dry
faeces
. Constipation
is usually harmless. The most common
cause is insufficient fibre in the diet (see
fibre, dietary
), because fibre assists the
propulsion of waste matter through the
colon
.
Other common causes include lack
of regular bowel movements due to poor
toilet-training in childhood or repeatedly
ignoring the urge to move the bowels.
Constipation in the elderly may be due to
immobility or to weakness of the muscles
of the abdomen and the pelvic floor.
Self-help measures such as establishing
a regular bowel routine, increasing the
amount of fibre in the diet, and drinking
more fluids are usually beneficial. Pro-
longed use of
laxative drugs
can impair
the normal functioning of the colon.
Constipation is occasionally a symptom
of an underlying disorder, especially if it
is part of a persistent change in bowel
habits after the age of 40, or if it is
accompanied by blood in the faeces, pain
on moving the bowels, or weight loss.
Conditions that may result in constipa-
tion include
haemorrhoid
s,
anal fissure
,
irritable bowel syndrome
, and narrowing
of the colon in, for example,
diverticular
disease
or cancer (see
colon, cancer of
).
constriction
A narrowed area, or the
process of narrowing.
contact dermatitis
A type of
dermatitis
caused by an allergic reaction to a sub-
stance that is in contact with the skin
and which would not cause a reaction
in most people exposed to it. Common
causes include nickel and rubber. (See
also
irritant dermatitis
.)
contact lenses
Very thin, shell-like, trans-
parent discs fitted on the
cornea
of the
eye to correct defective vision. General-
ly, contact lenses are used to correct
myopia
(shortsightedness) and
hyperme-
tropia
(longsightedness). There are several
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