Trabeculectomy, also called Filtration Surgery,
is a surgical procedure performed for treatment of glaucoma. The treatment involves removing
part of the trabecular meshwork and creating a new escape route for the aqueous humor.
When successful, it allows the aqueous fluid to drain from the eye into an area underneath
the conjunctiva where it is subsequently absorbed by the body’s circulatory system or filtered
into tears. In this procedure:
– A conjunctival pocket is created and maybe treated with Mitomycin or other antimetabolites
for a few minutes. These drugs are used to prevent scarring of the operation site. Scarring,
if occurs, may clog the new drainage canal, and is therefore the major reason the procedure
may fail. – A half thickness flap is then made in the
sclera and is dissected all the way to the clear cornea.
– A block of scleral tissue including part of the trabecular meshwork and Schlemm’s
canal is then removed to make a hole into the anterior chamber of the eye.
– As the iris may plug up this hole from the inside, a piece of the iris maybe removed
at this time. This is called iridectomy. – The scleral flap is then sutured loosely
back in place. These sutures can be released gradually during a couple of weeks after surgery.
This allows adjustment of the aqueous flow in order to achieve target pressure and to
avoid the complication of having a too low intraocular pressure.
– The conjunctiva is sewn back in place to cover the area.
After surgery, aqueous humor drains into a filtering area called a “bleb” under the conjunctiva.
Since the surgery is usually performed near the top of the eye, the bleb can easily be
concealed behind the upper eyelid.