| The Sneak-Thief of Sight
This animation shows progressive
vision damage from untreated glaucoma
THE EYE
To keep it light-weight for rapid movement, the
eye is made from soft, but strong tissues. However, like a camera, the eye needs to
maintain its shape so that it can focus light accurately. This is achieved by keeping the
eye firm, like a balloon. Clear fluid (the aqueous) is pumped into the eye from the
bloodstream carrying oxygen, sugars and other essential nutrients. Circulating around the
structures inside the eye, the aqueous is then drained through a meshwork back to the
blood to be renewed. Drainage is against resistance, so the eye's pressure is kept higher
than air pressure, but lower than the blood pressure.
Normal Eye
WHAT IS GLAUCOMA?
Glaucoma is the name given to a group of eye
diseases in which the optic nerve at the back of the eye is slowly destroyed. In most
people this damage is due to an increased pressure inside the eye - a result of blockage
of the circulation of aqueous, or its drainage. In other patients the damage may be caused
by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the
nerve, and/or a problem in the health of the nerve fibres themselves.
Over 300,000 Australians
have glaucoma. While it is more common as people age, it can occur at
any age. As our population becomes older, the proportion of glaucoma
patients is increasing.
WHAT ARE THE SYMPTOMS OF GLAUCOMA
Chronic (primary open-angle) glaucoma is the
commonest type. It has no symptoms until eye sight is lost at a later stage.
Damage progresses very slowly and destroys vision
gradually, starting with the side vision. One eye covers for the other, and the person
remains unaware of any problem until a majority of nerve fibres have been destroyed, and a
large part of vision has been destroyed. This damage is irreversible. It is progressive
and usually relentless. Treatment cannot recover what has been lost. But it can arrest, or
at least, slow down the damage process. That is why it is so important to detect the
problem as early as possible, to be able to start treatment with as little damage to the
vision as possible.
 Normal Vision |
 The same scene as it
might be viewed by a
person with glaucoma |
WHO IS AT RISK?
Although anyone can get glaucoma, some people
have a higher risk, those with
- a family history of glaucoma
- diabetes
- migraine
- short sightedness (myopia)
- eye injuries
- blood pressure
- past or present use of cortisone drugs (steroids)
People in these groups should
have their first eye check no later than the age of 35. For most people,
it is recommended
to have an eye
check for glaucoma by the age of 40.
HOW IS GLAUCOMA DETECTED?
Regular eye examinations are the best way to
detect glaucoma early.
A glaucoma test usually includes the following:
- optic nerve check with an ophthalmoscope
- eye pressure check (tonometry)
- visual field assessment if needed - this tests the
sensitivity of the side vision, where glaucoma strikes first
CAN GLAUCOMA BE TREATED?
Although there is no cure for glaucoma it can
usually be controlled and further loss of sight either prevented or at least slowed down.
Treatments include:
Laser (laser
trabeculoplasty) - this is performed when eye drops do not stop deterioration in
the field of vision. In many cases eye drops will need to be continued after laser. Laser
does not require a hospital stay.
Surgery
(trabeculectomy) - this is performed usually after eye drops and
laser have failed to control the eye pressure. A new channel for the
fluid to leave the eye is created.
Treatment can save remaining vision
but it does not improve eye sight.
WHAT ARE SOME OTHER FORMS OF
GLAUCOMA?
- Chronic (primary open-angle) glaucoma
is the most common form of this disease. However, other forms occur:
- Low-tension or normal tension glaucoma.
Occasionally optic nerve damage can occur in people with so-called
normal eye pressure. This form of glaucoma is treated in the same manner
as open-angle glaucoma.
- Acute (angle-closure) glaucoma. Acute
glaucoma is when the pressure inside the eye rapidly increases due
to the iris blocking the drain. An attack of acute glaucoma is often
severe. People suffer pain, nausea, blurred vision and redness of the
eye. Immediate medical help should be sought. If treatment is delayed
there can be permanent visual damage in a very short time. Usually,
laser surgery performed promptly can clear the blockage and protect
against visual impairment.
- Congenital glaucoma. This is a rare form
of glaucoma caused by an abnormal drainage system. It can exist at
birth or develop later. Parents may note that the child is sensitive
to light, has enlarged and cloudy eyes, and excessive watering. Surgery
is usually needed.
- Secondary glaucomas. These glaucomas
can develop as a result of other disorders of the eye such as injuries,
cataracts, eye inflammation. The use of steroids (cortisone) has a
tendency to raise eye pressure and therefore pressures should be checked
frequently when steroids are used.
History
of the word Glaucoma - Click Here
This page was updated on
10 February, 2006
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