For many glaucoma patients, internal eye pressure, or intraocular pressure (IOP), can be controlled for years with eye drops and other medications. Some people may eventually find, however, that their eye drops and medications have become ineffective or that they can no longer tolerate them. At this point, an eye care professional may suggest surgery. 

One type of glaucoma surgery uses a tube shunt drainage device, which is implanted in the eye and allows fluid (aqueous humor, or AH) to drain out of the eye.* To find out if you’re a good candidate for this type of surgery, learn about candidacy qualifications, differents types of shunt drainage devices, and potential surgical complications.

Are you a good candidate?

Tube shunts have shown to be successful in many types of glaucomas. Studies have also shown them to be more successful five years out than trabeculectomies. 

Qualifications for tube shunt candidacy will vary by doctor but may include: 

• Multiple types of glaucoma, such as glaucoma associated with uveitis or inflammation, neovascular glaucoma (associated with diabetes and other vascular diseases), pediatric glaucoma, traumatic glaucoma, and others 
• Undergone previous eye surgery, such as cataract surgery or trabeculectomy
• Insurance coverage (covered by Medicare and most major insurances)

How does a tube shunt work? 

A tube shunt drainage device is placed in the front part of the eye, between the cornea and the iris. The device pulls AH from the front of the eye to the back of the eye, which allows the eye’s veins to absorb and transport the fluid out of the eye cavity. 

There are many types of shunt devices, all of which are either valved or non-valved. Based on the type and severity of your glaucoma, your doctor will choose a shunt device that will work best for you. 

The most common type is a valved shunt device, called an Ahmed glaucoma valve. With this device’s valve mechanism, a tube allows the AH to be released out in one direction. This decreases IOP in glaucoma patients. For some patients, eye drops or medication may still be necessary to reach a normal IOP.

Other shunt devices, such as Baerveldt and Molteno, are non-valved, which means the shunt is not attached to the valve. Initially, this can cause IOP that is too low, but over time, scarring occurs and prevents the release of excess fluid. The non-valved option has been found to attain a lower IOP in comparison to valved shunt devices. 

What are the possible complications? 

Most tube shunt procedures are successful. If complications arise, they are usually short-lived or can be easily fixed. It is important, however, to be aware of the possible complications associated with the procedure, which include:

• Infection
• Failure of the tube shunt
• Bleeding inside the eye
• Fluid build-up inside the retina
• Double vision

*Ou, Y. (2020, Feb. 25). Glaucoma Surgery Series: Tube Shunt Drainage Devices. BrightFocus Foundation. https://www.brightfocus.org/glaucoma/article/glaucoma-surgery-series-tube-shunt-drainage-devices-glaucoma

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