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 most common 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 damaged, 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.
Who is at risk?
Although anyone
can get glaucoma, some people have a higher risk then the others:
- a family history of glaucoma
- diabetes
- migraine
- short sightedness (myopia)
- eye injuries
- blood pressure
- past or present use of cortisone drugs (steroids)
- Race - African Americans are significantly more likely to get
glaucoma than are Caucasians, and they are much more likely to suffer
permanent vision loss as a result. People of Asian descent are at
higher risk of angle-closure glaucoma and those of Japanese descent
are more prone to low-tension glaucoma.
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.
What are some of the forms of glaucoma?
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?
The treatment of glaucoma is aimed at reducing intraocular pressure.
The most common first line treatment of glaucoma is usually prescription
eye drops that must be taken regularly. In some cases, systemic medications,
laser treatment, or other surgery may be required. While there is
no cure as yet for glaucoma, early diagnosis and continuing treatment
can preserve eyesight.
Treatments include:
- Eyedrops - these are the most common form of treatment and
must be used regularly. The drops can be varied to best suit the patient
and the type of glaucoma.
- Laser (laser trabeculoplasty) - Laser trabeculoplasty helps
fluid drain out of the eye. A high-energy laser beam is used to stimulate
the trabecular meshwork to work more efficiently at fluid drainage.
The results may be somewhat temporary, and the procedure may need
to be repeated in the future.
- Surgery (trabeculectomy) - If eye drops and laser surgery aren't
effective in controlling eye pressure, you may need a filtering procedure
called a trabeculectomy. Filtering microsurgery involves creating
a drainage flap, allowing fluid to percolate into and later drain
into the vascular system.
- Drainage implants - Another type of surgery, called drainage
valve implant surgery, may be an option for people with uncontrolled
glaucoma, secondary glaucoma or for children with glaucoma. A small
silicone tube is inserted in the eye to help drain aqueous fluid.
Treatment for acute angle-closure glaucoma
Acute angle-closure glaucoma is a medical emergency. Several medications
can be used to reduce eye pressure as quickly as possible. A laser
procedure called laser peripheral iridotomy will also likely be performed.
In this procedure, a laser beam creates a small hole in the iris to
allow aqueous fluid to flow more freely into the front chamber of
the eye where it then has access to the meshwork for drainage.
Lifelong treatment
There is no cure for glaucoma. Patients with glaucoma need to continue
treatment for the rest of their lives. Because the disease can progress
or change silently, compliance with eye medications and eye examinations
are essential, as treatment may need to be adjusted periodically.
By keeping eye pressure under control, continued damage to the optic
nerve and continued loss of your visual field may slow or stop. The
optometrist may focus on lowering the intraocular pressure to a level
that is least likely to cause further optic nerve damage. This level
is often referred to as the target pressure and will probably be a
range rather than a single number. Target pressure differs for each
person, depending on the extent of the damage and other factors. Target
pressure may change over the course of a lifetime. Newer medications
are always being developed to help in the fight against glaucoma.
Early detection, prompt treatment and regular monitoring can help
to control glaucoma and therefore reduce the chances of progression
vision loss.
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