Cystic bleb formation and related complications in limbus- versus fornix-based conjunctival flaps in pediatric and young adult trabeculectomy with mitomycin C

Abstract

Objective Comparison of fornix- and limbus-based conjunctival flaps with respect to cystic bleb-related complications of trabeculectomy with high-dose mitomycin C (MMC) in pediatric and young adult glaucoma. Design Retrospective nonrandomized comparative interventional case series. Participants Thirty-seven patients. Methods Identification of patients aged <30 years from operating theater records from 1995 and 1996 of the Moorfields Pediatric Glaucoma Service who had trabeculectomy with an MMC concentration of ≥0.4 mg/ml. Over a 2-year period, 37 consecutive operations matching these criteria were performed by a single surgeon: 20 with a limbus-based flap and 17 with a fornix-based flap. Except for the conjunctival incision and associated alteration in antimetabolite application and wound closure, the surgical technique was not significantly different between the groups. Main outcome measures Bleb evolution and complications. Results The age at time of surgery, MMC concentration, history of one or more previous surgeries, and follow-up were similar in the 2 groups. The risk of cystic bleb formation was greater in the limbus-based flap group (90% in the limbus-based group vs. 29% in the fornix-based group; P<0.001). Late hypotony and bleb-related ocular infection were more common in the limbus-based flap group ( P<0.05) and occurred earlier. There were four episodes of bleb-related infection (20%) in the limbus-based group (three of these [15%] were bleb-related endophthalmitis) and none in the fornix-based group. Conclusions In pediatric and young adult trabeculectomy with high doses of MMC, limbus-based flaps may be more likely to develop serious bleb-related complications and may develop these earlier than fornix-based flaps. The higher rates of complications could be attributable to the differences in bleb morphology, with limbus-based flap cases more likely to develop cystic blebs.