Comparison of rabbit corneal subepithelial Haze after Epi-LASIK or PRK

Objective To evaluate whether epipolis laser in situ keratomileusis (Epi-LASIK) superior on decreasing Haze to photorefractive keratectomy (PRK)in rabbit eyes and explore its mechanism.Methods Epi-LASIK were performed in one eye of 18 New Zealand rabbits and PRK in the other eye.The changes of Haze,histological structure of cornea,expression of TGF-β2 in cornea were observed on the 1st week,4th week and 8th week postoperatively.Results Haze was statistically lighter following the Epi-LASIK(1.07±0.49,3.38±1.26)than PRK(2.38±1.04,5.00±1.95)on the 1st week and 4th week(Z1=-2.57,Z4=-2.41,P0.05)and no significant difference was found on the 8th week(Z8=-0.96,P0.05).Corneal histological structures were better in Epi-LASIK than PRK at the same time period.Following Epi-LASIK,the compactedness of corneal epithelium,integrity of basement membrane of corneal epithelium,adhesion of epithelium and stroma and regulation of collagen arrangement in Epi-LASIK were much better than in PRK.For the expressions of TGF-β2,no significant differences were seen in corneal epithelium on the 1st week and 4th week,nor in corneal stroma on the 1st week and 8th week between Epi-LASIK and PRK(P0.05),but there was a lighter expression of corneal epithelium after Epi-LASIK than PRK on the 8th week(t=-4.19,P0.05)and the same in corneal stroma on the 4th week(t=-2.53,P0.05).Conclusion Epi-LASIK is superior on decreasing Haze to PRK,and its epithelial flap reservation is important to decrease Haze.