Aqueous shunts, also known as tube shunts or glaucoma drainage implants, are drainage devices designed to lower intraocular pressure by draining aqueous humor from the interior of the eye to an encapsulated reservoir near the equator of the globe. In general, aqueous shunts have been used in eyes with poor surgical prognoses as listed in Table 18.1. The devices consist of one or more plates connected to a tube; the tube not only serves as the means of egress of aqueous from the eye but also prevents the opening into the eye from closing. Although there have historically been several devices used to keep an opening in the eye patent, Anthony Molteno was the first to design an implant that helped with the formation of a posterior episcleral filtering bleb. 1 Today, glaucoma drainage devices have become increasingly popular in the surgical management of a wide variety of routine and refractory glaucomas. 2 Clinical Indications for Aqueous Shunts

Prior failed glaucoma filtering surgery

Aphakic/pseudophakic glaucoma

Neovascular glaucoma

Uveitic glaucoma

Congenital glaucoma after failed angle surgery

Prior penetrating keratoplasty

Angle-closure glaucoma

Epithelial down growth

ICE syndrome

Possible primary surgery for simple glaucomas refractory to medical therapy