AIM: To investigate the probably mechanism of amniotic extraction inhibiting haze formation after epipolis laser in situ keratomileusis(Epi-LASIK)in rabbit cornea.

METHODS: Thirty rabbit corneas were performed with Epi-LASIK. All eyes were randomly divided into three groups: eyes treated with amniotic extraction(AE group), eyes treated with 1g/L dexamethasone(hormone group)and eyes treated with solvent(solvent control group). Haze grade evaluation was performed under the slit lamp after Epi-LASIK for 1, 4 and 8wk. The repair of corneal epithelium was observed by using HE staining, and the expression of NF-kB protein P65 was detected by immunohistochemistry. The expression levels of inflammatory cytokines(TNF-α, TGF-β1 and IL-1)and anti-inflammatory cytokines(IL-4, IL-10 and IL-13)were determined by ELISA.

RESULTS: HE staining showed that the basal cells of corneal epithelium were more uniform and arranged regularly in AE groups after Epi-LASIK for 1wk as compared with the hormone group and the solvent control group. After 4wk, there were a few of new collagen fibers in the superficial stroma of AE group, forming a small amount of scar. After 8wk, the corneal stroma of AE group showed a small amount of new collagen fibers, arranged regularly, and rarely formed scar. At the early stage(1 and 4wk), AE treatment has an obviously effect on inhibiting the secretion of inflammatory factors(TNF-α, TGF-β1 and IL-1)and anti-inflammatory factors(IL-4, IL-10 and IL-13), and the difference was statistically significant(P<0.01). Moreover, the activation of the NF-kB signaling pathway was significantly inhibited by treatment with AE in the early postoperative period(1 and 4wk).

CONCLUSION: Amniotic extraction may reduce the inflammatory response in corneal epithelial cells by inhibiting the NF-kB signaling pathway, thereby inhibiting the formation of collagen and scar and the occurrence of haze.