A defect of the
in w hich the
edges of the lids turn inwards, causing
the lashes to rub against the
transparent dome that forms the front
of the eyeball) and the
membrane that covers the white
the eye and the inside of the eyelid).
Entropion may be congenital (present
from birth), especially in overweight
babies. In addition, it is common in
elderly people, due to weakness of the
muscles around the lower eye, allowing
the lower lid plate to turn inwards.
Entropion of the upper or lower lid may
also be caused by scarring, such as that
Entropion in babies does not disturb the
eye and usually disappears w ithin a few
months. In later life,
the cornea, or problems with vision.
Surgery to correct entropion can pre-
vent such conditions.
throat surgery (see
To remove an
another structure surgically in such a
completely. A common example of enu-
cleation is the removal of an eyeball
while leaving the other structures in
place in the eye socket.
The medical term for bedwetting. It is a
common condition in children, and
boys are slightly more likely than girls
to be affected. The problem tends to
run in families.
maturation of nervous system func-
tions concerned with bladder control.
It may also result from psychological
stress. In a small number of bedwetters,
there is a physical cause, such as a
structural abnormality of the
may cause bedwetting in a
child w ho was previously dry. In cases
due to physical problems, the child also
If a child wets the bed persistently, tests,
may be performed
to rule out a physical cause. For bedwet-
ting that is not caused by a physical
disorder, treatment starts with training
the child to pass urine regularly during
the day. Systems such as rewarding the
child for each dry night (for example,
by putting stars on a chart) are often
successful. Getting the child to go to the
toilet just before bed may be helpful.
Punishing a child for bedwetting, how-
ever, w ill not help, and may actually
worsen the problem by making the
Alarm systems, known as buzzer and
pad systems, that involve placing
humidity-sensitive pad in the child’s
bed are available. The child is woken
by the alarm if urine is passed and
eventually learns to wake before start-
ing to pass urine.
The drug desmopressin is a synthetic
form of antidiuretic hormone (see
that may occasionally be given to redu-
ce the amount of water that is excreted
by the kidneys. Desmopressin is useful
on the occasional nights when a child
needs to stay dry, such as when staying
overnight with friends.
The study of the effects on health of
natural environmental factors, such as
climate, altitude, sunlight, and the pres-
ence of various minerals. Environmental
medicine overlaps somewhat with
in w hich the effects
on people of their working environ-
ments are studied.
of illness may be affected by certain
climates. For example, sufferers from
chest disorders, such as chronic
usually obtain some
relief from their symptoms in a warm,