Needling revision of trabeculectomies bleb morphology and long-term survival

Abstract

Purpose: To assess the long-term success rate and to determine factors that predict survival after 5-fluorouracil-augmented needling revision of poorly functioning trabeculectomy blebs.

Design: Prospective observational cohort study.

Participants: Eighty-one consecutive patients undergoing bleb needling.

Methods: Survival analysis was performed after a minimum of 2 years' follow-up. Cox proportional hazards regression analysis was used to test the association between survival and study variables, including bleb morphology.

Main outcome measures: Intraocular pressure (IOP) reduction by >20% and to <or=21 mmHg (definition 1) or IOP reduction by >20% and to <or=16 mmHg (definition 2).

Results: The mean follow-up period was 3.4 years. Survival rates were 64.2%, 54.3%, 45.7%, 31.9%, and 13.0% at 6, 12, 24, 36, and 48 months, respectively, with mean survival of 123.8 weeks (95% confidence interval [CI], 96.3-151.3; median, 74.0) using definition 1. Results for definition 2 were not significantly different. Survival time was shorter if multiple needlings were employed (P = 0.04) or if an immediate reduction in IOP to <or=10 mmHg was not achieved (P<0.001). Preneedling elevated bleb morphology was predictive of survival in comparison with flat blebs (P = 0.02), but this effect was significantly modified by (1) the interval between trabeculectomy and needling, (2) degree of bleb vascularization, and (3) presence of microcysts. Elevated blebs needled within 3 months of trabeculectomy or blebs that were also highly vascularized or microcystic were more likely to survive than flat blebs by factors of 4.7, 4.3, and 3.0, respectively (P = 0.002, P = 0.007, and P = 0.015, respectively). A higher proportion of blebs needled early after trabeculectomy survived to 12 months, but the timing of needling did not by itself significantly predict survival in the long term.

Conclusions: Needling with 5-fluorouracil is an effective intervention in the short to medium term, but long-term results show that additional intervention is necessary in the majority of cases. Bleb morphology can be used to predict success in recent, highly vascularized, or microcystic trabeculectomy blebs.