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A second type of surgery I have been monitoring is trabeculectomy.  Like the other glaucoma surgeries this surgery is done to alleviate pressure inside the eye.  Instead of inserting something into the eye to allow proper drainage trabeculectomies involve removing part of the eye's trabecular meshwork so fluid can drain through more easily and let the pressure decrease. First the surgeon punctures the conjunctiva and inserts some sponges soaked in one of two antimetabolites.  The first is mitomycin C (MMC), and the second is 5-fluorouracil (5FU).  This is done to help prevent scarring.  Antimetabolites are anything chemical which inhibits a normal metabolic process.  In this case it is fibroblasts which are being inhibited.  A cut is then made in the sclera and parts of the sclera, the trabecular meshwork, and Schlemm’s canal are removed in order to provide proper drainage.  The fluid will now drain into a small pocket near the new opening.  This area is called a bleb.  The bleb can usually be found at the limbus.  The fluid will then be absorbed into the bloodstream and lower the pressure on the eye.  If a bleb leaks or becomes flat, another trabeculectomy can be done at a different site. 

Here is a video of a trabeculectomy.  This is another graphic eyeball video so beware.

www.cybersight.org/data/1/rec_docs/73_Trabeculectomy_Dr%20Damji_256.wmv