Morphology of glaucoma drainage implantation.

Implantation of glaucoma drainage devices has become a standard procedure in various forms of intractable glaucoma. Indications include extensive conjunctival scanning at the upper limbal area, neovascular glaucoma (in addition to pars plana vitrectomy and endolasercoagulation), and secondary glaucoma due to uveitis or trauma. Implanting a glaucoma drainage device is an alternative to trabeculectomy with antimetabolites in young patients in whom delayed complications such as bleb-related endophthalmitis are more likely to occur. Intermediate-term success rates ranging from 70% to 90% are encouraging; however, long-term rates are substantially lower (< or = 50%). Major complications after glaucoma drainage device implantation include hypotony with suprachoroidal hemorrhage and shallowing of the anterior chamber, tube obstruction by fibrin clot, and long-term failure caused by bleb fibrosis. Various glaucoma drainage devices are commercially available; however, none of the designs has proved to be superior to the others.