Glaucoma
 Glaucoma
is a condition (more accurately, a group of related conditions) where
the optic nerve is slowly damaged. The optic nerve connects the eye to
the brain and damage caused by glaucoma causes irreversible loss of
sight.
The commonest form of glaucoma is called Primary Open Angle Glaucoma
(POAG). Typically, POAG causes damage, which initially affects the
peripheral vision which is not noticed by the patient. Without
treatment, damage may continue slowly, eventually causing loss of
central vision with blindness. The whole process from normal sight to
blindness can take many years. High eye pressure is the commonest
recognized cause of POAG, though about 30% of patients develop glaucoma
despite apparently normal eye pressure (Normal Tension Glaucoma, NTG).
Because early glaucoma is symptomless it is usually noted as part of
the routine examination undertaken by an optometrist (optician). The
optometrist will identify glaucoma by measuring the eye pressure,
examining the optic nerve and evaluating the field of vision.
 Glaucoma
is rare in people under the age of 40. It tends to run in families
(though there are many patients who have no recognized history in their
family). It is more common in people of Black African/Caribbean descent
and in short-sighted people.
Treatment of POAG and NTG depends upon reducing the eye pressure to a
level low enough to prevent further damage. We talk of
'target-pressures'; eye pressures at which further damage to the optic
nerve is unlikely. Every patient has a different 'target-pressure' which
will typically be approximately 30% lower than the eye pressure at which
damaged first occurred (the pressure before treatment was started).
Initial treatment involves use of eye drops. There are several different
glaucoma drops available, which are administered from one to four times
a day. Treatment is usually required for life.
Once diagnosed, glaucoma requires long-term follow-up. The frequency
of follow-up is dependant upon factors such as the patients' age and
severity of disease. Each visit to the doctor involves reviewing
treatment, measuring eye pressure, examining the eye and optic nerve and
assessing the visual field. If the glaucoma is getting worse treatment
will be changed.
 Glaucoma
surgery is reserved for the minority of patients who do not respond to
drop treatment. Surgery may involve lasers (laser trabeculoplasty, laser
iridotomy or diode laser) or traditional surgery (trabeculectomy).
Trabeculectomy surgery is usually undertaken under local anaesthetic.
Trabeculectomy entails making a small drainage hole into the eye, which
allows the fluid within the eye to drain out slowly, thereby reducing
pressure. Most trabeculectomy operations reduce eye pressure long-term.
Common problems in the short term (1-2 months post surgery) include
discomfort, redness, low pressure, high-pressure and reduction in
vision. Most operations settle well after this period. Longer-term, a
minority of patients can suffer irritation, increase in pressure, low
pressure or cataract.
Early glaucomatous optic disc cupping
with haemorrhage |
Severe glaucomatous optic disc cupping |
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