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What is the purpose of glaucoma surgery?
Glaucoma surgery reduces eye pressure. The purpose of reducing intraocular
(within the eye) pressure is to prevent further vision loss from glaucoma.
Glaucoma surgery usually does not improve vision.
Why is surgery performed for glaucoma?
Medicine — usually in the form of eye drops — or glaucoma laser can lower
pressure and treat glaucoma. However, sometimes these do not adequately lower
the intraocular pressure. In addition, some patients have side effects from the
eye drops while others cannot afford their medicine. Glaucoma laser is
quicker, easier, more convenient, and safer than surgery. However, it does not
always adequately lower the pressure, and its effects might wear off months or
years later.
For some, glaucoma surgery is the best option. Surgery reduces intraocular
pressure to lower levels than can be achieved by medicine or laser, and might also reduce or
eliminate the need for long-term glaucoma medicine. The lower pressure
achieved by surgery has been shown to provide a greater chance of preventing
further loss of vision from glaucoma.
Is there more than one type of glaucoma surgery?
The most common glaucoma surgery performed in the United States is called a
"trabeculectomy." During this operation, a partial thickness channel is
created on the upper part of the eye, through the sclera (white part of the
eye). This creates a fluid-filled pocket, sometimes called a "glaucoma
filtering bleb," that allows the fluid from the eye to spread outward
around the eye, reducing eye pressure.
Full-thickness filtering surgery was an earlier form of glaucoma surgery. It
was found to be highly effective, but tended to cause a greater number of side
effects from the pressure becoming too low. Occasionally, it is performed for
selected patients.
In the late 1990s, some glaucoma subspecialists advocated
non-penetrating filtering surgery. This has the advantage of reducing the risk
of the intraocular pressure becoming too low immediately after surgery, but
seems to have a disadvantage in that there is a higher failure rate and need for
repeat surgery for glaucoma.
What is a glaucoma implant?
There are several types of implants for glaucoma treatment.
Glaucoma implant surgery is a somewhat longer and more technically involved
procedure compared to trabeculectomy. Glaucoma implants have two components:
- A small tube that is placed in the front or back of the eye to collect
fluid
- A plate connected to the tube that forms a natural chamber of tissue to
collect and release the fluid from your eye
It is generally reserved for cases of severe glaucoma due to more unusual
conditions, such as abnormal vessels in the front of the eye of some people with
diabetes, and glaucoma caused by ocular inflammation. Implant surgery is also
used in some individuals who have previously had a trabeculectomy that was not
successful.
What is the recovery period after glaucoma surgery?
Immediately after surgery you can use your eyes. There will be some blurring
in the operated eye. We recommend that people wear their glasses during the
daytime and tape an eye shield over their operated eye at bedtime. Most people
are able to engage in normal activities, but it is recommended that patients
avoid heavy straining or lifting for a few days, and avoid bumping or rubbing the
eye.
Are there risks of glaucoma surgery?
Any eye surgery has some risk. The glaucoma operation might fail and require
glaucoma medicine or another operation. Frequently, the eye pressure becomes
very low. This is usually harmless over a short period of time. However, over a long
period of time, this might cause vision changes. Occasionally, there is a leak
from the surgery, which often closes naturally. Any eye surgery has the risk of
bleeding in the eye or infection, but the risk is usually less than one percent
(1%), and precautions are taken to reduce that risk.
However, these risks must be compared to the risks of uncontrolled glaucoma,
which can lead to a total, permanent loss of vision, if the pressure cannot be
controlled with eye drops, laser, or surgery.
What can be done to prevent failure of glaucoma filtering surgery?
In the last two decades, two medicines have been used to reduce scarring
after glaucoma surgery. One is 5-fluorouracil and a second is mitomycin C. Both
are medicines that were initially developed for cancer treatment and have been
found to reduce the scarring after surgery, particularly in higher risk cases.
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