If all medical therapy fails to lower the eye pressure adequately a surgery to create an alternative drain for the eye may become necessary. A trabeculectomy creates a pathway for fluid to leave the eye and form a small elevation underneath the skin on the surface of the eye called a bleb. From the bleb, the fluid can then be absorbed by the tissues surrounding the eye. This bypasses the eye’s own internal drainage system and can allow for the pressures to be lowered dramatically. Ideally, the procedure allows for discontinuation of pressure lowering medications. Studies show that 50% of patients no longer need medications after surgery. Another 35-40% of patients will still need medications after surgery, but their glaucoma is under much better control.
There are certain inherent risks with any surgical procedure. The same holds true for filtration surgery. Below is a list of potential side effects and complications.
- Hypotony (very low eye pressure) – This is a serious complication, but advances in the surgical techniques and implants have reduced the risk of hypotony.
- Scarring – Scarring is a side effect that is seen in about 20% of patients. Scarring can lead to an increase in the eye pressure by closing the drainage passage. Most commonly, scarring is seen in African-Americans, patients with inflammatory disease and young patients. Treatment for scarring includes releasing sutures and bleb needling (a fine gauge needle is used to remove the scar tissue that is covering the drainage area). During filtration surgery, the doctor may use medicines such as Mitomycin C or Fluorouracil to help prevent scarring.
- Bleb Leaks and Infections – It is common for blebs to leak, especially thin blebs. This can be observed as soon as hours after the procedure, or may not occur for years. If left untreated, leaking blebs can lead to serious complications, including blindness. Leakage can also lead to infection, bleeding, inflammation and flattening of the eyeball. When a bleb begins to leak, additional surgery may be needed. This is why it is important to be closely monitored after filtration surgery.
- Cataracts – The incidence of cataracts after filtration surgery is high. Eventually, everyone develops a cataract, it is just that the process is often accelerated after glaucoma surgery. Cataract surgery may be performed after filtration surgery if needed. In many cases it is preferable to remove cataracts prior to having a trabeculectomy. This can maximize the chances of long-term success of the surgery.
Both trabeculectomies and tube implants are good procedures but there is a chance that the pressure goal may not be achieved. The reason for these surgeries to not have a 100% success rate is because a significant portion of their efficacy depends on how the eye heals. The extent of healing is only partially under our control. Too little healing and the drain can work too well. This can lead to very low pressures which can cause it’s own set of problems. Too much healing and scar tissue can close the drain off. For these reasons, once we decide that a surgical procedure is necessary it is important to keep in mind that you may need to continue your eye drops. It may even mean that an additional surgery is necessary at some point in the near or distant future. This is why surgery is often performed only after any less invasive measures have been exhausted. You can feel confident that we will try to avoid surgery if possible and that no matter what the outcome, we will be there for you to make sure we do everything possible to care for your eyes.