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Glaucoma Drainage Implant Surgery

Glaucoma drainage devices, such as the Baerveldt and Ahmed implants, are useful in patients who are poor candidates for glaucoma filtration surgery. These patients have risk factors, such as multiple previous eye operations, that make it more likely that a filtration operation would fail due to scarring.

Glaucoma drainage implants come in different shapes and sizes. With each of them, a plastic tube is inserted into the front of the eye between the cornea and the iris. The tube drains fluid from inside the eye, and allows the fluid to collect within a reservoir in the eye socket, from where it is removed by the body. Glaucoma drainage implants are not used to improve vision, but to preserve vision by lowering the intraocular pressure. In this respect, they are completely different from the type of implant which is used during cataract surgery.

Glaucoma drainage implants are not new. In fact, the idea of controlling intraocular pressure with an external tube has been around for almost 100 years. With improved surgical techniques and implant materials, glaucoma drainage implants have become a safe and effective tool in the fight against glaucoma.

Glaucoma implants

Glaucoma implants come in many shapes and sizes. A clear thin tube is placed into the front part of the eye, and is connected to a reservoir outside the eye.

Gaucoma Drainage Implants are for those

in whom a more standard glaucoma operation, such as trabeculectomy, is not expected to be successful.
who have previously undergone eye surgery more than once.

Occasionally, a glaucoma drainage implant will be recommended as an initial surgical procedure, particularly in eyes that are at high risk of scarring. Compared to the channel made with trabeculectomy, the tube of the glaucoma implant is less likely to become blocked by scar tissue.

What to expect on surgery day

The clear tube is barely visible through the cornea of a patient who has had a corneal transplant. The reservoir cannot be seen because it is covered by the eyelid and outer portions of the eye.

You will arrive at the surgery center several hours prior to your procedure. Once you have been checked-in, 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 local anesthesia.

Glaucoma implants are usually placed in the area underneath the upper eyelid. Using advanced microsurgical techniques and equipment, your doctor will suture the implant to the sclera, and insert the tube into the front chamber of the eye just in front of the iris. Unless the lid is pulled back, neither you nor your family will notice the implant. With the upper lid retracted, a white patch may be noted. This is a patch that covers the tube and prevents irritation.

There is little discomfort following surgery except for a minor irritation. Patients usually go home within a few minutes of the end of the operation and are instructed to relax for the rest of the day. Most patients resume normal activities within a few days. Eye drops will be prescribed to ensure healing without infection or inflammation. 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 improve the drainage of fluid from the eye.

Realistic expectations

The goal of glaucoma implant surgery is to lower intraocular pressure and preserve vision. It will not restore vision that has already been lost. Since glaucoma drainage implants are used in patients with more complicated problems, the success rate of the operation might be slightly lower than for a standard trabeculectomy. Although most patients do well, some will require further treatments. In more difficult cases when glaucoma drainage implant surgery does not lower the intraocular pressure enough, other procedures, including insertion of a second implant, might be necessary.

Serious complications with glaucoma drainage implant surgery are uncommon, but like any surgical procedure, there are some risks. Having a surgeon who specializes in glaucoma and is highly experienced in insertion of these devices can significantly minimize risks.

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