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

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 (IOPratio) 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 IOPratio ≥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.

Conclusions

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.

Keywords:Bevacizumab, trabeculectomy, filtering bleb, bleb scarring, mitomycin-C. Philipp J Ophthalmol 2012;37:66-72