8
As already discussed, glaucoma may appear with a great variety of
causes and mechanisms.
Some common disorders such as “pseudoexfoliation syndrome”
and “pigment dispersion syndrome” result in the precipitation of
particles in the draining angle. This restricts the amount of aqueous
that can be drained, causing accumulation and rise in intraocular
pressure with time.
The lens in the eye (which is behind the iris) may also be found guilty
of blocking the angle in various ways. In
phacolytic glaucoma
the
release of phacic material by a hyper-mature cataract can block the
angle, causing painful rise in pressure. In the rarer
phacoanaphylactic
glaucoma
the pressure rises due to an inflammatory reaction
against the lens, which causes a decreased function of the angle.
In
phacomophic glaucoma
the swelling of a hyper-mature cataract
pushes the iris forward and blocks the angle, but this can also be
caused by a dislocated or subluxated lens.
Different types of ischemia such as diabetes or carotid artery disease
promote the formation of a membrane of pathological vessels,
the
“neovascular membrane”
. In time, this membrane grows and
constricts, drawing the iris forward, blocking the angle and causing
the so-called
“neovascular glaucoma”
.
Glaucoma can also be caused by other mechanisms like ophthalmic
tumors, trauma, or surgical procedures.
Congenital glaucoma constitutes a specific group of glaucoma
which
manifests usually in the first three years of life
and occurs
in 1:10.000 births. As the eye at this age is still concessive, a rise in
intraocular pressure causes enlargement of the globe and results in
the clinical appearance called
“Buphthalmos”
as the eye appears
like the eye of a bull. Furthermore, the child is agitated, has excess
lacrimation, photophobia and irritated eyes causing closure and
rubbing. All these symptoms should alarm the parents to urgently
visit an ophthalmologist.
Other types of glaucoma
Congenital glaucoma
pressure returns to the pre-medication level.
Long term intake of
cortisone can keep high levels of intraocular pressure for even a few
months after its termination.
