Trabeculectomy and other perilimbal surgical procedures result in formation of a bleb that acts as a reservoir at the limbus. These blebs are associated with various adverse effects such as bleb leaks, bleb-related infections, and bleb dysesthesia.7,8 Postoperative fibrosis leading to failure of trabeculectomy leads to excessive scar tissue formation in the perilimbal area, making that area less suitable for a second surgical procedure.9 These outcomes have led to the increasing use of GDDs in the management of glaucoma. Surgery using GDDs results in formation of the bleb 8 to 10 mm posterior to the limbus. The presence of the biomaterial of the GDD and the accumulation of aqueous humor in the subconjunctival space stimulates an inflammatory reaction and fibrosis, which leads to formation of a well-defined bleb surrounding the GDD plate. The combination of ongoing inflammation and fibrosis leads to failure of the operation. From a clinical standpoint, the bleb proceeds through 3 stages: (1) a hypotensive phase, which lasts approximately 1 to 4 weeks during which the IOP is typically low, and the bleb is ill defined and diffuse and exhibits congested blood vessels; (2) a hypertensive phase, which lasts from 1 to 6 months and is associated with increased IOP, and the bleb becomes localized and well defined with formation of a dense fibrous capsule separating the aqueous humor from the conjunctival blood vessels; and (3) a stable phase, which is achieved at the end of 6 months and is characterized by the presence of a bleb with no or little inflammation and well-controlled IOP, usually in the midteens (range, 15-17). The incidence of the hypertensive phase has been reported to be between 10% and 50% and varies with the various GDDs.1 In general, it is accepted that the incidence is lower with the Baerveldt implant compared with the AGV.10 During this phase, the IOP can potentially increase to 30 to 50 mm Hg. The overall failure rate of GDDs is approximately 10% each year, leading to a 50% failure rate at 5 years. This is the result of continued fibrosis. One-time application of antifibrosis drugs such as mitomycin C or fluorouracil during the operation has not been effective in reducing fibrosis in surgical procedures incorporating GDDs,11 unlike that after trabeculectomy. In the tube-vs-trabeculectomy study comparing the Baerveldt implant with trabeculectomy in patients with previously failed trabeculectomies, during the first year of follow-up, in the GDD group, IOP was more likely to be controlled, persistent hypotonia or repeat operation because of glaucoma was averted, and there were fewer postoperative complications compared with the trabeculectomy with the mitomycin C–treated group.12 A recent article suggested increased success with lower incidence of the hypertensive phase in patients receiving repeated injections of fluorouracil into the bleb after application of mitomycin C during surgery in patients undergoing AGV implantation.13 Thus, surgery using a GDD has several advantages over traditional trabeculectomy. However, the inflammatory reaction that results in the hypertensive phase and the continued fibrosis leading to complete failure are important problems that must be overcome to improve the surgery. The creation of a slow-release mitomycin C drug-coated GDD is an attempt to overcome these problems.