When glaucoma continues to progress despite the use of medication regimens and possibly laser treatments, a glaucoma filtration procedure (trabeculectomy) may be recommended. In general, a glaucoma filtration procedure is recommended when these other methods of glaucoma management have failed or have insufficiently controlled the progression of glaucoma. However, in some cases, a glaucoma filtration procedure may be recommended before other methods of treatment are attempted. This decision is based on the type of glaucoma, the degree that it has advanced, the general health of the patient and ability to comply with treatment regimens, and other circumstances.

 
     
  On the day of surgery, one should expect to have several eye drop medications applied multiple times to the eye for approximately one hour prior to the procedure. Finally, the eye drop anesthetics or local anesthetic is applied just prior to the procedure. 

Once in the operating room, your eye will be “prepped” for surgery with sterilizing solutions. Usually, a semi-opaque sterile drape will be applied over the operative field, using a small instrument to hold your lids apart for the procedure. Your eye should be entirely comfortable during the operation. Your surgeon may recommend mild sedation during the procedure, and this is usually determined on a case-by-case basis. 		 
     
 
The goal of the glaucoma filtration procedure is to create a new passageway by which aqueous fluid inside the eye can escape, thereby lowering the pressure. The escape route, however, is not directly to the external surface of the eye, as this would obviously allow access for bacteria to infiltrate the eye, and thus lead to potential infection.  
 
     
  The filter, therefore, allows the drainage of fluid from inside the anterior chamber of the eye to a “pocket” created between the conjunctiva, which is the outermost covering of the eye, and the sclera, which is the underlying white anatomical structure of the eye. The fluid is eventually absorbed by blood vessels.  
     
  In many cases, medication to control scarring, and thus to help prevent closure of the filtration site, is applied to the eye during the operation or just afterwards. These medications, known as Mitomycin C and 5-Fluorouracil (5-FU), will be used in some cases and not others, depending on both surgeon and patient variables.  
     
  After Your Operation:  
 

In most cases, a patch and shield will be placed over your eye on the day of surgery. This is usually removed later that day or the day after surgery and eye drop medications are begun. Your surgeon will usually want to evaluate your eye on the day of surgery or on the first post-operative day. At that time, depending on pressure in the eye, your surgeon might elect to cut sutures on the flap of the filter to modulate the filtration process. This is often done with a laser while in the office. Antibiotic and anti-inflammatory eye drop medications are continued after surgery for up to 6 weeks or more.

  
     
  Does surgery eliminate the need for medication?  
  You will certainly need medications after surgery, perhaps for the first 4 to 10 weeks. After the filter site of your eye has entirely healed, whether you will need glaucoma medications will depend largely on the pressure in your eye as well as your peripheral vision (based on a visual field test). In most cases, dependence on glaucoma medication is reduced, and in some cases, glaucoma medications are no longer required. Your eye surgeon will determine whether medicines are appropriate or not based on your final outcome with surgery.  
     
  Is there still pressure in the eye after surgery?  
  Yes. However, after a glaucoma filtration procedure, the pressure may be too low or too high, depending on the degree of filtration. Your surgeon will use many techniques as well as medicines to modulate this effect after surgery. Once healing is complete, usually 6 to 8 weeks after surgery, a new “baseline” pressure is usually established based on the degree of filtration created by the combination of the surgery and subsequent healing.  
     
 
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