| Objective: Trabeculectomy is still the mainstay of surgical management of reducing the intraocular pressure(IOP) in glaucoma. After trabeculectomy, the development of conjunctival and episcleral fibrosis occurs as a result of progressive fibroblast migration, proliferation, collagen deposition, and angiogenesis at the site of filtration, which is the most common reason for trabeculectomy failure. Application of anti-metabolic drugs mitomycin C(MMC) and 5-fluorouracil(5-FU) can reduce the scarring of the filtering bleb, but there is a dangerous complications such as postoperative hypotony, thin-walled bleb, bleb leakage and even endophthalmitis. Recent studies showed that vascular endothelial growth factor(VEGF) can promote endothelial cell proliferation, increased vascular permeability, promote blood vessel formation and promote scarring. So we through study the morphological and histopathological changes of filtering bleb, to evaluate the efficacy of bevacizumab as an antifibrotic agent after trabeculectomy in rabbits, and provide a new idea for further anti-scarring method of clinical glaucoma surgery.Methods: Forty New Zealand rabbits were randomly divided into four groups. Trabeculectomy was performed on the right eyes of each rabbit by the same surgeon. The rabbits received a single subconjunctival injection of 0.05 m L bevacizumab(25 mg/m L) at the end of the operation in group A. The same dose of bevacizumab was respectively injected at the end of operation as well as 3 days and 7 days after operation in group B, and 0.05 m L normal saline solution was used in the same way in group D. In group C, MMC cotton patch with 0.2 mg/ml was placed under the Tenon's caplsule and scleral flap for 3 minutes during operation. The IOP, bleb height, area and shape were evaluated during the 28-day period. The animals were sacrificed on postoperative day 14 and 28, respectively for the histopathologic examination of filtration channel. The expression of CD31 in the filtration channel was detected by immunohistochemistry for the calculation of microvessels.Results: No significant difference in the postoperative IOP was found among the groups at each time point(F=0.88, P=0.47). The bleb morphology was larger and the surface vessels were sparse in group B, when compared with the other groups at postoperative 7 days. The blebs remained for 27, 19, and 13 days in groups B, A, and D, respectively, and were the same in groups A and C. The percentages of collagen deposition areas were(49.18±1.54)%,(26.41±1.23)%,(50.68±1.87)% and(70.63±1.81) % at postoperative day 14 in groups A?B?C and D, respectively, with the largest area in group D, and collagen deposition area percentage was significantly reduced in group B compared with group A(all P<0.05). The percentage of collagen deposition area was(66.82±1.53)% at postoperative day 28 in group B, while complete scarring was seen in the other groups. The microvascular number in group B(13.13±0.54) was significantly lower when compared with groups A?C and D at 14 days(all P<0.05). After 28 days, the microvascular number in group B(3.51±0.31) was more than that of groups A?C and D. The difference was statistically significant(all P<0.05).Conclusions: All the experimental results suggest that:(1) Subconjunctival injection of bevacizumab after trabeculectomy could inhibit filtration channel neovascularization, slow the process of filtration channel scarring,and may be a new treatment strategy to alleviate filtration channel scarring and improve the success rate of surgery.(2) Subconjunctival injection of bevacizumab at the ending of operation and postoperative 3, 7 days could prolong bleb existence time.(3) The effect of subconjunctival injection of bevacizumab to suppress filtration channel scarring is not less than MMC in short-term. |
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