Topical Bevacizumab as Adjunctive Therapy for Bleb Survival after Trabeculectomy in the Rabbit Model

Abstract

Objective: To determine the effect of topically administered bevacizumab on bleb survival and histology after trabeculectomy in rabbit eyes.

Methods: This is an experimental interventional comparative animal study. Sixteen rabbit eyes underwent trabeculectomy, 8 of which were enhanced with intraoperative mitomycin-C. Eyes were randomized to receive either topical balanced salt solution (BSS) or topical bevacizumab at a concentration of 12.5 mg/mL. Intraocular pressure, bleb dimensions and vascularity grading were measured. IOP was recorded as a ratio of IOP of the experimental operated eye divided by the IOP of the contralateral control eye (IOP_ratio) as a function of time. Bleb morphology was recorded as a percentage of the maximum estimated bleb volume (% bleb) as a function of time. Bleb failure occurred if IOP_ratio ≥0.8, or if % bleb=0. The eyes were then submitted for histopathological analysis after bleb failure has occurred.

Results: In plain trabeculectomy, the mean bleb survival in terms of IOP were 6.3 and 9.2 days in the BSS and topical bevacizumab groups respectively (ρ=0.25). In mitomycin-C-enhanced trabeculectomy, the mean bleb survival was 16 and 18.2 days respectively (ρ=0.40). In plain trabeculectomy, mean bleb survival in terms of bleb morphology were 8 and 12.2 days for the BSS and bevacizumab groups respectively (ρ=0.08). In enhanced trabeculectomy, mean bleb survival were 19.5 and 20 days respectively (ρ=0.99). Mean vascularity grading were 2 and 1.9 for the BSS groups, and 1.6 and 1.4 for the bevacizumab groups.

Conclusion: Topical bevacizumab as adjunctive therapy after trabeculectomy, whether plain or enhanced with mitomycin-C, showed a trend towards prolonged bleb survival, even though the results of this study were not statistically significant.