Glaucoma - Medications

Surgery

If medications do not control eye pressure, or if they create intolerable side effects, surgery may be necessary in a small percentage of people with glaucoma. The standard procedures are usually one of the following:

• Filtration surgery (trabeculectomy). This procedure opens the full thickness of the drainage area.
• Laser trabeculoplasty. This procedure partially opens the drainage area. It does not reduce pressure to the extent of trabeculectomy but it has fewer adverse effects.

Filtration Surgery (Trabeculectomy)

The Procedure. Filtration surgery has been used for more than 100 years with only minor modifications. It uses conventional surgical techniques known as full-thickness filtering surgery or guarded filtering surgery (trabeculectomy).

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• The surgeon creates a sclerostomy, a passage in the sclera (the white part of the eye) for draining excess eye fluid.
• A flap is created that allows fluid to escape without deflating the eyeball.
• The surgeon may also remove a tiny piece of the iris (called an iridectomy) so that fluid can flow backward into the eye.
• A small bubble called a bleb nearly always forms over the opening, which is a sign that fluid is draining out. Although surgeons aim for a thick bleb, which poses less risk than a thin one for later leakage, the ideal operation would have no bleb at all.

The procedure has a high success rate. About 50% of patients no longer need medication after surgery. Thirty-five to 40% of those who still need medication have better control of their glaucoma.

A newer instrument called a trabectome has allowed for a less invasive type of trabulectomy surgery, which can be performed before a traditional trabulectomy or tube shunts, if needed. The trabectome procedure uses an electrosurgical pulse to remove a small section of the trabecular meshwork.

Side Effects. Many of the serious side effects or complications that occur with filtration surgery involve blebs (blister-like bumps).

• Bleb Leaks and Infections. Blebs, particularly thin ones, commonly leak. Leakage can occur early on or sometimes as late as months or years after surgery. Untreated, such leaks can be serious and even cause blindness. Late-onset leakage significantly increases the risk for infection as well as a number of other serious conditions, including bleeding, a flattening of the eye ball, and harmful inflammation. Surgical repair is the most effective way of managing leaking blebs, although drug therapies, pressure patching, and other nonsurgical techniques may be tried first. Due to the dangers of leaking blebs, doctors recommend lifelong monitoring after surgery.
• Scarring. In up to 20% of cases, scars form around the incision, closing up the drainage channels and causing pressure to rebuild. Scarring is a particular problem in young patients, African-Americans, and patients who have taken multiple drugs, have had an inflammatory disease, or have had cataract surgery. Releasing the surgical stitches used in the procedure may help prevent scarring and pressure build-up. A second procedure called bleb needling can sometimes open up the scarred area and restore drainage. With this technique, the tip of a very fine hypodermic needle is used carefully to cut loose the particles closing off the drainage area.
• Cataracts. The procedure is highly associated with the development of cataracts over time. Because cataracts are associated with glaucoma anyway, it is not entirely clear whether the cataracts are caused by the surgery or would develop in any case.