BLEEDING, DYSFUNCTIONAL UTERINE
B
BLOOD VESSEL DEFECTS
In rare cases, abnormal bleeding is the
result of a blood-vessel defect or
scurvy
(a disorder that is caused by a defi-
ciency of
vitamin
C). Elderly people and
patients on long-term courses of
cortico-
steroid drugs
may suffer m ild abnormal
bruising due to loss of skin support to
the smallest blood vessels. Treatment is
rarely required in these cases.
~ y ---------- ----------------
Abnormal
bleeding
from
(womb) with no obvious
also
menorrhagia
).
the
uterus
cause. (See
bleeding gums
See
gingivitis
.
bleeding, occult
Bleeding that is not obvious to the
naked eye (such as that w hich occurs
w ithin the intestine) and that may be
detected only by tests. (See also
o
ccult
blood, faecal
) .
bleeding time
An assessment of the functioning of
platelets (the tiny cell fragments within
the blood that play a vital role in
blood
clotting
)
by
measuring the
speed at
w hich they form plugs to stem bleeding
from damaged blood vessels. Two small
cuts are made in the forearm and the
time taken for the bleeding from these
cuts to stop is recorded.
blepharitis
Inflammation of the eyelids, with red-
ness, irritation, and scaly skin at the lid
margins. Blepharitis may cause burning
and discomfort in the eyes and flakes or
crusts on the lashes. The condition is
common, tends to recur, and is some-
times associated with dandruff of the
scalp or
eczema
.
Severe blepharitis may
lead to
corneal ulcers
.
In many cases,
treatment of associated dandruff with
an antifungal shampoo w ill result in
improvement of the blepharitis.
blepharoplasty
A cosmetic operation to remove droop-
ing,
w rinkled
skin
from
the
upper
and/or lower eyelids. Blepharoplasty is
usually performed under local anaes-
thetic (see
anaesthesia, local).
blepharospasm
Prolonged, involuntary contraction of
one of the muscles controlling the eye-
lids, causing them to close. It may be
Appearance before (top) and after (bottom)
Blepharoplasty involves the removal of a crescent-
shaped section of skin and underlying fat from
each eyelid.
due to
photophobia
(abnormal sensitivity
of the eyes to light), to damage to the
cornea
(the transparent dome that forms
the front part of the eyeball), or to
dys-
tonia
(abnormal muscle rigidity), for
which
botulinum toxin
(a muscle relaxant)
treatment is highly effective.
blind loop syndrome
A condition in w hich a redundant area
or dead end (blind loop) in the small
intestine becomes colonized with bac-
teria. The bacteria break down bile salts,
w hich are necessary for the absorption
of fat and certain vitamins. This results
in poor absorption of fats and abnormal
faeces. Blind loop syndrome may result
from surgery or a
stricture
(narrowing)
in the intestine as a result of a disorder
such as
Crohn’s disease
.
It is charac-
terized
by
steatorrhoea
(pale yellow,
foul-smelling, fatty, bulky faeces that are
difficult to flush away), tiredness, and
weight loss.
Antibiotic drug
treatment is
usually effective, but the condition may
recur
if the
underlying
abnormality
cannot be corrected.
blindness
Inability to see. Definitions o f blindness
and partial sight vary. In the UK, blind-
ness is defined as a corrected
visual acuity
of
3/60
or less, or a
visual field
of no
more than 20 degrees, in the better eye.
CAUSES
Loss o f vision may result from injury
to, or disease or degeneration of, the
eyeball; the optic nerve or the nerve
pathways that connect the eye to the
brain; or the brain itself.
Eyeball Normal vision depends on an
uninterrupted passage of light from the
front of the eye to the light-sensitive
retina at the back. Anything that pre-
vents light from reaching the retina can
cause blindness.
Various
disorders
can lead to
the
clouding of the cornea at the front of
the eye. These disorders include
Sjogren’s
syndrome
(in w hich the eyes become
excessively dry),
vitamin A
deficiency,
chemical damage, infections, and injury.
Corneal ulcers,
w hich most commonly
develop
after
severe
infections,
can
cause blindness due to scarring of the
cornea.
Uveitis
(inflammation
of the
iris, ciliary body, or choroid), can also
cause loss of vision.
Cataract
(cloudiness of the lens) is
another common cause of blindness. It
is usually the result of the lens becom-
ing less transparent in old age, but is
occasionally
present
from
birth
or
develops in childhood.
Diabetes mellitus,
hypertension
(high
blood pressure), or injury can all cause
bleeding into the cavity of the eyeball
and a subsequent loss of vision. Bleed-
ing into the fluid in front of the lens
(see
hyphaema
) or behind the lens (see
vitreous haemorrhage
) can also result in
loss of vision.
Disorders of the retina that may result
in blindness include age-related
macular
degeneration
(degeneration of the cen-
tral area of the retina, w hich occurs in
old age);
retinopathy
due to diabetes or
to hypertension;
retinal artery occlusion
or
retinal vein occlusion
(blockage of the
blood flow to and from the retina);
reti-
nal detachment;
certain types of tumour,
such as
retinoblastoma
and malignant
melanoma affecting the eye (see
melan-
oma, malignant);
and
retinal haemorrhage
(bleeding into the retina), caused by
diabetes, hypertension, vascular disease,
or injury.
In
glaucoma,
excessive fluid pressure
within the eyeball causes degeneration
of nerve fibres at the front end of the
optic nerve.
Nerve pathways The light energy that is
received by the retina is transformed
into nerve impulses that travel along the
optic nerve and nerve pathways into the
brain. Loss of vision may result if the
conduction of these nerve impulses is
impaired.
Reasons for damage to nerve pathways
include pressure caused by a tumour in
the orbit (the bony cavity that contains
the eyeball); a reduced blood supply to
106
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