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Glaucoma Tube Shunts

What is a tube shunt drainage device?

Ahmed-valve            Baerveldt-valve

A glaucoma tube shunt consists of a very small plate with a unique valve system (i.e. Ahmed Valves) that regulates your eye pressure. Some tube shunt devices are “not valved” and have to be tied with a suture until some healing takes place around the plate on the device (i.e. Baerveldt Valves). What these devices all have in common is that they consist of a plate with a tube that drains the fluid out of the eye, thereby reducing the eye pressure. The implant is outside the eye, but is covered by the skin of the eye (conjunctiva) so it can’t be seen or felt. 

When is a tube shunt procedure indicated?

Glaucoma tube shunt surgery may be performed in patients with glaucoma that is not controlled by medications, laser treatment, or trabeculectomy. If a trabeculectomy has already been performed and failed, the next surgical intervention will likely be a glaucoma tube shunt (although is some cases, a second trabeculectomy may be recommended). There are some cases in which a glaucoma tube shunt may be the first surgical intervention, as opposed to a trabeculectomy. These cases include, but are not limited to patients with neovascular glaucoma, inflammatory glaucoma (glaucoma secondary to uveitis), or patients with a prior corneal transplant. 

What is done during the tube shunt procedure?

First, the conjunctiva is opened and retracted in the upper-outer part of the eye. The body of the device is sutured to the white part of the eye (sclera). After the body of the device is sutured in place, a small tunnel is created through the sclera to enter the anterior chamber of the eye. The tube, which extends from the body of the device, is inserted into the eye’s anterior chamber. A patch graft is placed over the tube to prevent it from eroding through the conjunctiva. Although the device is sutured onto the top of the eye, it is completely covered by the eye’s outer covering, the conjunctiva. Most, if not all, of the device will not be visible behind the upper eyelid after the surgery. In some cases, a small bulge may be noticed on the upper-outer aspect of the eyelid. 

What should I expect if I have a tube shunt procedure?

The procedure is done under local anesthesia and IV sedation in the outpatient surgery center (you will need to receive a shot next to the eye to put the eye asleep). Eye drops are used to numb the surface of the eye. The eye will be cleaned and a sterile drape will be put over your face and body, leaving only your eye uncovered. This keeps the area of the operation clean and sterile. Your eye will be held open by a “lid speculum,” so you will not blink during the surgery. After the surgery is over, a patch and shield will be placed over your eye. This will be removed the day after surgery on your first post-operative visit. You should expect to be seen frequently until the eye completely heals. For many people, this may take six to eight weeks. During this time, you will be taking frequent and multiple eye drops. The postoperative care varies greatly and may include suture removal and/or other minor procedures to maximize the outcome of the surgery. During this time, you will need to restrict yourself from strenuous activities.

Will my glaucoma be cured with the glaucoma tube device?

No. There currently isn’t a cure for glaucoma. Any vision that has already been lost prior to the surgery, in general, will not return. Tube shunt surgery only lowers your eye pressure. By lowering the eye pressure, the goal is to either stop or slow down your loss of vision. Sometimes this goal is not possible.

Can I stop my eye drops after the surgery?

You will definitely need eye drops for two or more months after the surgery. Some people do not have to take eye drops after that period. Many people will eventually need some glaucoma eye drops to keep their pressure under control. In some cases, people will be taking fewer eye drops than they were before the surgery. The need for eye drops after tube shunt surgery varies greatly and is determined by your type of glaucoma and the rate it is progressing.

What are some risks for tube shunt surgery?

All eye surgery has some risks. Operations are not done unless the benefits outweigh the risks. Risks include, but are not limited to, bleeding, infection, hypotony (very low pressure), scarring, swelling, retinal detachment, droopy eyelid, double vision, loss of vision, or even loss of the eye. Sometimes the tube fails and needs to be flushed or replaced. In general, many of the risks are not common, however you may want to discuss the benefits and risks with your surgeon should you have any further questions.