Intravitreal Bevacizumab as Adjunctive Therapy for Bleb Survival in Trabeculectomy in Rabbit Eyes

Objective: To determine the effect of intravitreally administered bevacizumab, alone or as adjunct to mitomycin-C, after trabeculectomy on bleb survival and histology in rabbit eyes. Methods: An experimental, interventional, comparative, animal study consisting of 16 rabbit eyes underwent trabeculectomy, 8 of which were enhanced with intra-operative mitomycin-C. Eyes were randomized to receive intravitreal bevacizumab at a concentration of 12.5 mg/mL. Intraocular pressure (IOP), bleb dimensions, and vascularity grading were obtained. IOP was recorded as a ratio of the 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) over time. Bleb failure occurred if IOPratio ≥0.8, or if % Bleb =0. Eyes were enucleated and submitted for histopathological analysis. Results: In terms of IOP, mean bleb survival of the plain trabeculectomy group was 7.00(±0.00) days compared to 11.00 (±1.00) days in the intravitreal bevacizumab group (p=0.02). In mitomycin-C-enhanced trabeculectomy eyes, the mean bleb survival was 15.25 (±0.75) days compared to 19.00 days in the intravitreal bevacizumab group (p=0.002). In terms of bleb morphology, bleb survival were 9 (±1.00) and 13 (±0.00) days for the plain trabeculectomy and intravitreal bevacizumab groups respectively (p=0.02); and 18.25 (±0.75) and 20.00 (±0.58) days for the trabeculectomy with mitomycin and intravitreal bevacizumab groups respectively (p=0.11). Mean vascularity grading were 1.67 (± 0.33) and 1.33 (± 0.33) for the plain trabeculectomy and bevacizumab groups and 1.50 (±0.59) and 1.25 (±0.25) for the mitomycin and bevacizumab groups respectively (p=0.72). Histologic analysis showed less fibroblast count for eyes treated with bevacizumab. Conclusion: Intraoperative intravitreal bevacizumab as adjunctive therapy after trabeculectomy, whether plain or enhanced with mitomycin-C, was associated with improved bleb survival rates in the rabbit model.