Filtration Surgery (Trabeculectomy)
Trabeculectomy also referred to as a guarded filtration procedure, is the most common surgery performed to reduce internal eye pressure. The surgery creates an alternative pathway for fluid to leave the eye.
Trabeculectomy is preformed at The Eye Surgery Center under monitored anesthesia care (MAC) and a local injection around the eye. Under the operating microscope the clear movable conjunctiva covering the eye is opened and a partial thickness small flap is made in the upper part of the sclera (white fibrous tissue). Under the base of this flap a small opening is made to allow internal fluid (aqueous) to leave the eye. The sleral flap is then sutured down and adjusted to control fluid outflow. The conjunctiva is the sutured closed watertight. Escaping aqueous forms a blister or “bleb” under the eyelid from where it is absorbed into the blood stream.
Filtration surgery is for those:
- who have been diagnosed with glaucoma
- whose doctor has determined that filtration surgery is an appropriate treatment for their condition
What to expect on surgery day:
You will arrive at the surgery center 30-60 minutes prior to your procedure. Once you have been checked-in and settled comfortably, you will be prepared for surgery. The area around your eyes will be cleaned and a sterile drape will be applied. You may be given a sedative to help you relax. Your eye will be numbed with topical or a local anesthesia. When your eye is completely numb, an eyelid holder will be placed between your eyelids to keep you from blinking.
Using advanced microsurgical techniques and equipment, your doctor will create a tiny new channel between the inside of your eye and the outside of your eye. A small section of tissue will be removed, creating a channel, to allow fluid to pass through the blocked drainage network onto the white (sclera) of the eye. The incision will be closed with small stitches and covered with the thin outer tissue of the eye, called the conjunctiva. Blood vessels in the conjunctiva will carry the draining fluid away.
Antimetabolites are frequently used during trabeculectomy to prevent the bleb from scarring closed. Mitomycin-C and 5-fluorouracil (5-FU) are the most commonly used antimetabolites for glaucoma surgery.
After surgery patients are followed very closely to monitor the bleb function. Anti-inflammatory drops are required for weeks, sutures may need to be adjusted or cut to enhance outflow. Many patients may need some additional glaucoma medications to achieve low pressures; surgical revisions of dysfunctional blebs may be necessary.
Follow-up visits are necessary to monitor your eye pressure. It may take a few weeks to see the full pressure-lowering effect of this procedure, and adjustments may need to be made to the filter during this period. These adjustments may include:
- injection of small amounts of chemotherapeutic agents
- loosening or removal of one or more stitches
- finger pressure to the eye to force fluid through the filter
- numbing the eye and opening the channel slightly with a fine instrument
- placing a contact lens over the eye
The success rate for this type of surgery is approximately 80 percent in cases where no surgery has been done on the eye before. However, everyone’s eyes are unique and many people do require further treatments. In more difficult cases where even filtration surgery doesn’t prevent damage to the ocular nerve, it may be necessary to perform other types of procedures.
Serious complications with filtration surgery are extremely rare, but like any surgical procedure, it does have some risks. Going to a specialist experienced in filtration surgery can significantly minimize the risks.
If you and your doctor decide that filtration surgery is an option for you, you will be given additional information about the procedure that will allow you to make an informed decision about whether to proceed. Be sure you have all your questions answered to your satisfaction.