Rosmarinic Acid Suppresses Subconjunctival Neovascularization in Experimental Glaucoma Surgery

Purpose: Excessive subconjunctival scarring is associated with increased angiogenesis and leads to filtration failure in glaucoma surgery. In this study, we describe that rosmarinic acid (RA) has anti-angiogenic activity during wound healing in a rabbit model of glaucoma surgery. Methods: Forty New Zealand rabbits underwent an experimental trabeculectomy and were randomly allocated into two treatment groups: RA group - treated with subconjunctival injections of 0.1 ml RA (15 mg/ml; n = 20) - and control group - treated with subconjunctival injections of 0.1 ml balanced salt solution (n = 20). The in vivo effect of RA was investigated after 5 and 15 d by measuring the intraocular pressure (IOP; with Tonopen) and bleb area and vascularity (using the Moorfields Bleb Grading System). Vascularization was also studied by counting histological blood vessels and by immunohistochemistry of vascular endothelial growth factor (VEGF) at the surgical site and by quantification of vessels in chicken's chorioallantoic membrane (CAM), treated with AR 500 mu g/ml for 48 h. Results: On the fifth day, eyes of RA group displayed higher bleb area (3.6 +/- 0.2 versus 1.8 +/- 0.2; p = 0.004) and lower vascularity (3.0 +/- 0.5 versus 4.0 +/- 0.4; p = 0.009) than controls; however, difference in IOP reduction was not significant (-1.4 +/- 0.3 versus -0.8 +/- 0.3mmHg; p = 0.226). Proportion of vessels/field (4.6 +/- 0.5 versus 10.4 +/- 0.9; p = 0.008) and VEGF immunostaining (15,347 +/- 3788 versus 31,043 +/- 3230; p = 0.019) also declined with RA treatment. However, at the 15th day, none of the parameters were different between the groups, except for vessels/field proportion (5.4 +/- 1.0 versus 10.6 +/- 1.6; p = 0.035). CAM exposed to AR inhibited vascularization (-45.67 +/- 4.74%; p<0.001). Conclusion: These data indicate RA has a short-term anti-angiogenic effect and could be a potential modulator of neovascularization during subconjunctival healing at glaucoma filtration surgical sites.