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Glaucoma
GLAUCOMA
Glaucoma is increasingly common
as a person ages. Typically it is very insidious meaning that it comes
on slowly and is hard for a patient to recognize. It is for this reason
that it is extremely important for patients over fifty to regular eye
examinations. Part of the examination is a measurement of the pressure
inside the eye. This is called intraocular pressure or IOP. If the
pressure inside of the eye is too high it causes a slow and progressive
injury to the optic nerve.
The optic nerve is vital
to site. It is the pathway by which visual images are conducted to the
brain. If the optic nerve is damaged even slightly, vision will be
impaired. If it is damaged severely then vision is permanently lost.
The optic nerve consists of millions of fibers that pass the images of
what one is looking at directly to the vision interpretation center in
the cerebellum of the brain.
There are two types of glaucoma
that can raise the pressure within the eye. The first type is far and
away the most common and is called open angle glaucoma. Fluid is
continually produced within the eye, and this fluid requires an area to
drain through in order to avoid excess accumulation within the eye. The
“angle” describes the area that the fluid enters to go to the drainage
area. When a patient has open angle glaucoma it means that the anatomy
of the drainage system is open; however, there is a blockage farther
along the system much like if a drain was open in a sink and the
drainage pipe was blocked a few feet from the opening. Open angle
glaucoma is a slowly progressive illness in most situations and will
result in significant vision loss over time if left untreated. It is
most commonly treated with drops that lower the IOP.
The other form of glaucoma that
increase IOP is called closed angle glaucoma. This form of glaucoma
occurs suddenly and without warning and results in closure of the
opening of the drainage system. This can result in eye pain, headache,
and possibly nausea or vomiting. It requires immediate attention, and
the patient will typically have enough symptoms to force a trip to the
doctor. Thankfully this type of glaucoma is usually effectively treated
with surgical intervention to permanently open the entrance to the
drainage area.
There is another form of
glaucoma that is not associated with increased intraocular pressure.
This type of glaucoma is rare and is called normal tension glaucoma of
NTG. Doctors are not sure why patients with normal eye pressure
(between 12 and 22) begin to suffer damage to the optic nerve; however,
one large study shows that even though these patients have a normal IOP
they seem to benefit from drops to lower the pressure. There are also
other forms of treatment such as laser surgery or filtering surgery.
There is yet another type of
glaucoma that is called secondary glaucoma. This means that the
glaucoma is the result of something else happening to the eye that
results in a problem with the drainage system. This can occur if the
eye begins to form abnormal new blood vessels that block the opening to
the drainage system. It can also occur if there is a shedding or
flaking of a substance from the lens that blocks the angle. Secondary
glaucoma can occur from blunt injury to the eye, and can occur
immediately after the injury or many years later. There are other forms
of secondary glaucoma as well; however, the main ones are listed here.
Lastly there is pediatric
glaucoma. Children can be born with glaucoma or it can develop in the
first several months or within the first few years of life. It is
typically treated with drops or with the types of surgery used for
closed angle glaucoma that are alluded to above.
Additional information about glaucoma can be found on any of the numerous sites listed on this search.
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