lens. It is connected at its outer edge to
the ciliary body and has a central aper-
through which light
enters the eye and falls on the retina.
The iris constantly contracts and dilates
to alter the size of the pupil, which con-
trols the amount of light that passes
through the pupil.
An inflammation of the iris, now
often termed an “anterior
A mineral essential for the forma-
tion of certain
(the oxygen-carrying pigment in red
blood cells), and
gen-carrying pigment in muscle cells). It
is found in foods such as liver, cereals,
fish, green leafy vegetables, nuts, and
beans. During pregnancy, supplements
may be needed. Iron deficiency leading
to anaemia (see
anaemia, iron deficiency
is usually caused by abnormal blood
loss, such as from a
periods, but may also be due to diet.
Iron supplements may cause nausea,
abdominal pain, constipation, or diar-
rhoea and may colour the faeces black.
Excessive iron in the tissues is a feature
, which results in
organ damage, commonly
A large machine formerly used
to maintain breathing, especially in
people paralysed by
iron lung has been replaced by more
efficient means of maintaining breath-
irradiation of food
The treatment of
food with ionizing
to kill bacte-
ria, moulds, insects, and other parasites.
It improves the keeping qualities of
food and is a means of controlling some
. It does not
destroy bacterial toxins, however, and
. Irradiation does
not render food radioactive.
Cleansing of a deep
wound by repeatedly washing it out with
a medicated solution or sterile saline.
trolled contractions of the muscles in the
wall that may cause urge incon-
occur temporarily if there is a urinary
tract infection (see
); a catheter
present within the bladder; a bladder
stone (see c
alculus, urinary tract
); or an
obstruction to the outflow of urine by
cases, symptoms may be relieved by
; other treatment is
directed at any underlying cause. Blad-
der training may also be used.
irritable bowel syndrome (IBS)
combination of intermittent abdominal
pain and constipation, diarrhoea, or
bouts of each, that occurs in the absence
of other diagnosed disease. IBS affects
10 -2 0
per cent of adults; it is twice
as common in women as in men, usually
beginning in early or middle adulthood.
It is usually recurrent throughout life
but is unlikely to lead to complications.
Symptoms include intermittent cramp-
like pain in the abdomen, abdominal
distension, often on the left side, tran-
sient relief of pain by bowel movement
or passing wind, sense of incomplete
evacuation of the bowels, and excessive
wind. Anxiety and stress tend to exacer-
bate the condition.
If constipation is the main problem, a
high-fibre diet or bulk-forming agents,
, may be
helpful. Short courses of
may be given for persistent diar-
prescribed to relieve muscular spasm.
have proved effective in some cases.
Insufficient blood supply to
a specific organ or tissue. It is usually
caused by disease of the blood vessels,
, but may also
result from injury, constriction of a ves-
sel due to spasm of the muscles in the
vessel wall, or inadequate blood flow
due to inefficient pumping of the heart.
Symptoms depend on the area affected.
to widen the blood vessels or,
in more severe cases, an
One of the bones that form the
lower part of the
Nursing procedures (also called
barrier nursing) designed to prevent a
patient from infecting others or from