Trabeculectomy is an effective procedure to control intraocular pressure (IOP) and to prevent progression of vision loss. One of the risks associated with this procedure is oversized and exuberant blebs, which may result in reduction of visual acuity. Understanding the mechanisms and prognosis of this complication is important for evaluating and selecting the proper treatment. Large blebs overhanging the cornea may cause visual acuity loss if they directly obstruct the visual axis, but they can also be problematic due to their effect on lid movements and resultant drying of the cornea. Furthermore, the overhanging, “beer-belly” bleb can also induce corneal dryness as well as irregular astigmatism. The trabeculectomy surgical technique itself may also affect the development of oversized blebs. Some authors believe that fornix-based conjunctival flaps result in more diffuse and less elevated blebs that are less likely to encroach on the limbus, compared to limbus-based conjunctival flaps. Limbusbased conjunctival flaps are limited by scar formation at the conjunctival wound site, preventing posterior movement of aqueous and forcing bleb elevation toward the limbus. The use of antifibrotics, such as mitomycin-C and 5-fluorouracil, during filtering procedures may predispose to the development of larger ischemic blebs. Thin-walled ischemic blebs may continue to enlarge months to years postoperatively as the bleb wall constantly remodels. Various laser treatments can be used to contract oversized blebs. Fink et al used argon laser photocoagulation to shrink large blebs in 4 eyes; however 2 eyes developed leaks. Sony et al treated 3 eyes with large blebs using frequency-doubled Nd:YAG photocoagulation after painting the area of the blebs with gentian violet to enhance the laser absorption. Several treatment sessions resulted in bleb shrinkage and remodeling. Lynch et al applied a continuous wave multimode Nd:YAG laser in 4 eyes with symptomatic large blebs, 3 of which had undergone previous trabeculectomy with antifibrotic agents. Two eyes required retreatment, and one eye developed a bleb leak afterward. These reports indicate that laser application success has been limited, and bleb leaks may occur.
Cyanoacrylate tissue glue for wound repair in early posttrabeculectomy conjunctival bleb leak: a case series
