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.