Filtration surgery, also known as trabeculectomy, is often performed in patients with unstable, or poorly controlled, glaucoma. It has been in widespread use since the 1970s, and is still the most commonly performed surgical procedure in the treatment of glaucoma. Patients who are benefit from filtration surgery are those who have already tried one or more glaucoma medications and/or laser trabeculoplasty, and who continue to experience vision loss or optic nerve damage.
Filtration surgery aims to bypass the eye's natural drainage system by creating a new drainage pathway through which fluid can leave the eye. The fluid passes through a tiny window that is usually placed in the top of the eye in the sclera (white part of the eye). The fluid collects under the conjunctiva (the thin membrane that covers the slera) and forms a small sac, or bleb, which is usually hidden under the upper eyelid. From there the fluid is removed by the eye's normal blood vessels.
What to expect on procedure day and beyond:
You will be asked to arrive at the surgery center one to two hours before the scheduled time of surgery. After checking in and being admitted to the preoperative area, a nurse will measure your blood pressure, pulse, and other vital signs. You will be given an intravenous line through which you might receive a light sedative.
Next, you will be taken into the operating room, where your anesthesiologist will give you more intravenous sedatives to make sure you are fully relaxed. You will be awake and breathing on your own throughout the operation, but your anesthesiologist will be by your side the entire time to make sure you are comfortable and pain free. The operation usually takes about thirty minutes. At the conclusion of surgery, a patch will be placed on your eye, and will remain on your eye until the next day. You will be allowed to go home after resting in the recovery area for about fifteen minutes.
The next day, you will have a postoperative appointment in our office. The patch will be removed from your eye and your eye pressure will be measured. In the two to three weeks following surgery, patients commonly experience redness, swelling, a scratchy sensation, and blurred vision in the operated eye. These symptoms are temporary and gradually fade away. Most patients are asked to refrain from strenuous exercise for at least one week after surgery, but light exercise, reading, and computer use are OK. You will need to use antiinflammatory eyedrops for at least four to six weeks following surgery; your doctor will give you specific instructions on how soon you can taper your drops. In the weeks following surgery, you will need to make several postoperative visits, when some adjustments might need to be made. These include cutting the sutures with a laser and administering anti-scarring medications. If all goes well, your eye pressure will be brought under control, and you will cut down, or eliminate, your use of glaucoma drops.
Filtration surgery is successful in up to 80 percent of cases in the first year, although the success rate drops somewhat after each successive year. The most common cause of failure is scarring, which sometimes happens despite our best efforts to prevent it. In the event of scarring and a rise in pressure, further procedures can be done to reopen the drain, sometimes in the office. In some cases a return to the operating room is unavoidable. It is important to understand that glaucoma filtration surgery will not bring back vision that has been lost; it will only help to stabilize the nerve damage and prevent more vision loss in the future. While serious complications from filtration surgery are rare, risks do exist, as with any operation. Your doctor will help you decide whether the benefits of the surgery outweigh any risks.