Study On Effect Of Anti-scarring After Glaucoma Filtering Surgery With Chitosan

Objective: Chitosan were injected in conjunctival flap and sclera flap of the rabbits' eyes after resection of trabecular to study the effect of anti-scarring with the chitosan after glaucoma filtering surgery. Methods: 20 adult rabbits were randomly selected into two groups. 32 eyes of 16 rabbits were selected for the group 1 and the other 8 eyes of 4 rabbits were selected for the group 2. In the group 1, one eye of all the rabbits was considered as experimental group (group A) and the other as experimental control group (group B). In the group 2, both eyes of all the rabbits were considered as normal control group (group C). Glaucoma filtering surgery combined with chitosan injection in conjunctival flap and sclera flap after surgery was conducted in the group A. Glaucoma filtering surgery only was conducted in the group B. And no operation and injection was conducted in the group A. Formation of the filtering blebs, changes of intraocular pressure were observed in after 1w, 2w, 4w and 12w of the operation. And then eyeballs of the rabbits were extirpated and used into histopathology study. HE staining and immuno-histochemical staining were made to observe the results of filtering passage and scar forming, and quantity of the fibroblast cells after 1w, 2w and 12w of the operation were compared. Results: Conjunctiva hyperaemia decreased postoperative in 1 st day to 2nd day, and then disappeared gradually. It disappeared significantly sooner in the group A then in the group B (P<0.01). Before the operation, the intraocular pressures were (2.25±0.43) kPa in group A, (2.29±0.34) kPa in group B and (2.30±0.15) kPa in group C, respectively. After 12 weeks of the operation, the intraocular pressures were of the 3 groups were significantly different (P<0.01), and they were (2.31±0.19) kPa in group A, (3.04±0.11) kPa in group B and (2.41±0.14) kPa in group C, respectively. The rate of filtering bleb (+) was higher in the group A than in the group B. After 1 week of the operation, in the group A, quantity of the fibroblast cells near the incision of filtering passage was less than in group B. The filtering bleb was unobstructed and the framework of the filtering bleb was loose. Quantity of the fibroblast cells in filtering passage after 1 week, 2 weeks and 12 weeks of the operation in group A were significantly different from that of in the group B (P<0.05). And the results of the immuno-histochemical staining showed that the positive expression rate of VEGF( Vascular endothelial growth factor, VEGF)was higher in the group B, and lower in the group A and the group C. Conclusion: As an assistant medicine for glaucoma filtering surgery, chitosan had certain effect on inhibition of fibrous tissue proliferation and scar forming in filtering passage. After operation, the filtering passage kept unobstructed and the intraocular pressures continuously depressed. It showed that success rate of the glaucoma filtering surgery was increased efficiently.