EYE TUMOURS
nel, w hich drains fluid from the eye),
which can lead to
glaucoma
(a sudden
increase in fluid pressure in the eyeball).
Injuries to the centre of the
cornea
(the transparent dome that forms the
front of the eyeball) impair vision by
causing scarring. Damage to the
lens
(the component of the eye responsible
for focusing) may cause a
cataract
(loss
of transparency) to form.
eyelashes
Hairs that are arranged in rows at the
edge of each eyelid and normally curve
outwards. The purpose of the eyelashes
is to prevent dust and debris from
entering the eye. The lashes become
finer and fewer as a person ages.
Growth in an abnormal direction
may be due to injury to the eyelid or,
more
commonly,
to
an
infection.
Severe
blepharitis
(inflammation of the
lid margins) may destroy the roots of
the lashes.
Trachoma
,
an infection in
w hich the lid can be distorted by scar-
ring, may lead to
trichiasis
,
in w hich
the lashes turn inwards and rub against
the
cornea
(the transparent dome that
forms the front of the eyeball).
eye, lazy
A popular term for
amblyopia
(in w hich
normal vision has failed to develop in
an otherwise healthy eye). The term
“lazy eye” also refers to a convergent
squint
(in w hich one eye turns inwards).
eyelid
A fold of tissue at the upper or lower
edge of an orbit (eye socket). The eye-
lids
are
held in
place by
ligaments
attached to the socket’s bony edges.
They consist of thin plates of fibrous
tissue (called tarsal plates) covered by
muscle and a thin layer of skin. The
inner layer is covered by an extension of
the
conjunctiva
(the transparent mem-
brane that covers the white of the eye).
Along the edge of each lid is a row of
eyelashes
.
Immediately behind the eye-
lashes are the openings of ducts that
lead from the meibomian glands, which
secrete the oily fluid in tears.
The eyelids act as protective shutters,
closing almost instantly as a
reflex
action
if anything approaches the eye. They
also spread the tear film across the
cornea
(the transparent dome that forms
the front of the eyeball).
DISORDERS
Disorders affecting the eyelids include
a
chalazion
(a swelling of a meibomian
gland),
blepharitis
(inflammation of the
edge of the eyelid), and a stye (a small
abscess at the root of one of the lashes).
Certain disorders affect the shape and
position of the eyelids. These include
entropion
(in w hich the eyelid margin
turns inwards),
ectropion
(in w hich the
eyelid margin turns outwards), and
pto-
sis
(in w hich the eyelid droops down,
covering all or part of the eye).
Myokymia (twitching of the eyelid) is
common, and usually caused by fatigue.
Blepharospasm
(prolonged
contraction
of the eyelid) is usually due to a condi-
tion such as photophobia
(abnormal
sensitivity of the eyes to sunlight) or a
foreign body. The skin of the eyelid is a
common site for a
basal cell carcinoma
.
eyelid, drooping
See
ptosis
.
eyelid surgery
See
blepharoplasty
.
eye, painful red
A common combination of eye symp-
toms that may be due to any of various
eye disorders.
Conjunctivitis
(inflammation
of the
conjunctiva, the transparent membrane
covering the white of the eye) is the
most common cause of redness and irri-
tation in the eye.
Uveitis
(inflammation
of the iris, choroid, and/or ciliary body)
is a common cause of dull, aching pain;
this may be due to swelling in the front
part of the eye and spasm in muscles
around the iris (the coloured part of the
eye). The redness is caused by widening
of blood vessels around the iris.
Another cause of pain and redness in
one eye is acute closed-angle
glaucoma
(a sudden increase in pressure within
the eyeball). The pain is severe and may
be accompanied by nausea, vomiting,
and blurred vision. Increased blood flow
in the surrounding blood vessels causes
redness in the white of the eye.
There are additional causes of painful
red eye including
keratitis
(inflammation
of the cornea, the outer protective layer
of the eye), w hich usually occurs as a
result of a
corneal ulcer
,
and a foreign
body in the eye (see
eye, foreign body in
) .
eye-strain
A common term used to describe ach-
ing or discomfort in or around the eye.
Eye-strain is usually due to a headache
caused by fatigue, tiredness of muscles
around
the
eye,
sinusitis
,
blepharitis
(inflammation of the eyelid margins),
or
conjunctivitis
(inflammation of the
conjunctiva, the transparent membrane
that covers the whites of the eye).
eye teeth
A common name for the canine
teeth
.
eye tumours
Tumours of the eye are rare. However,
when eye tumours do occur, they are
usually painless and cancerous.
TYPES AND TREATMENT
Retinoblastoma This
is
a
cancerous
tumour of the
retina
(the light-sensitive
inner layer at the back of the eye) that
may occur in one or both eyes and most
often affects children. Retinoblastoma
may be treated by
radiotherapy
,
laser
treatment
,
or
cryosurgery
(freezing), but
the eye may have to be removed to
prevent spread of the tumour.
Malignant melanoma This form of cancer
occurs in the
choroid
(the layer of tissue
between the retina and the sclera, the
white of the eye) and usually affects
middle-aged or elderly people. There are
no symptoms in the early stages, but
the tumour
eventually causes
retinal
detachment
and distortion
of vision.
Small malignant melanomas can be
destroyed by laser treatment, but the eye
may need to be removed to prevent
spread of the tumour.
Secondary eye tumours If cancer else-
where in the body spreads to the eye,
secondary tumours develop. Symptoms
depend on a tum our’s location and
growth rate. Secondary eye tumours
may be controlled by radiotherapy;
however, the primary tumour w ill need
to be treated separately.
Basal cell carcinoma This is the most
common type of tumour of the eyelid. It
may be caused by excessive exposure to
sunlight. The tumour usually has a
crusty central crater and a hard rolled
edge. In the early stages, a basal cell
carcinoma of the eyelid may be treated
by surgery, radiotherapy, or cryosurgery.
If the tumour becomes large, the eyelid
may need to be removed.
E
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