The Observation Of Early Corneal Healing Response After Rabbit PRK And Flap-free EPI-LASIK In Different Cutting Depth

Objective Study the expression of cellular morphology, inflammatory cells, and cell factors bFGF,NF-κB after rabbit PRK and flap-free EPI-LASIK in corneal epithelium and stroma with different depth cutting. In order to discuss early corneal healing response in two surgery methods, and it can provide the theory basis for clinical work.Methods The twenty-two experimental rabbits were randomly divided into three groups, ten for high cutting groups(-10.00D), ten for low cutting groups(-3.00D),and left two without treatment for control groups. Establishing experimental animal model, make flap-free EPI-LASIK on right eyes, PRK on left eyes. The two rabbits were randomly executed at 1d,3d,5d,7d in high and low cutting depth, eight only. The left fourteen were killed at 7d. Take corneal organization along the corneal margin. The animal eyes were observed using fluorescent dyes after surgery daily, including ocular basic status, corneal epithelium of healing and the time to heal. To investigate cells morphological changes of corneal and inflammatory reactions using HE dyeing, while counting inflammatory cells in quantity by light microscopy. Expression of bFGF and NF-κB were detected when early corneal wound healing by immunohistochemistry. Analysis positive cells by light microscopy, and applied to Pro Plus 5.0 Image analysis system for quantitative analysis. Detect corneal stroma cell apoptosis with TUNEL method. All of data apply SPSS17.0 to do statistical analysis.Results 1,Status of eyes: The eyes of PRK, symptoms serious and mitigated at 3d, The eyes after flap-free EPI-LASIK, without corneal edema, and the symptoms were disappeared after 3d, in high cutting group, the symptoms were more serious. 2,Corneal epithelial healing: Observation of fluorescence staining, in high cutting group , corneal epithelial healing time after PRK, the shortest time was 3d, the longest time was 6d, with an average of 4.33d. Corneal epithelial healing time after flap-free EPI-LASIK, the shortest time was 3d, the longest time was 5d, with an average of 3.83d. Lowly cutting group healing time was a bit shorter, The two surgeries had a little difference.3,The cornea morphologic changes: In low cutting group, after PRK surgery, corneal epithelium excessive proliferation, cells disordered, including a mass of vacuoles cells, the stromal layer disordered, and inflammatory cells infiltrate. While after flap-free EPI-LASIK, there was not obvious hyperplasia, epithelium cells and stromal layers slightly disordered, invisible clear vacuoles cells and inflammation cells infiltrate. In high cutting group, corneal morphologic changed obviously.4,inflammatory: In low cutting group, There was no significant difference in the expression of inflammatory cells in the cornea between PRK and flap-free EPI-LASIK(t=2.20,P>0.05).But in high cutting group, There was a significant increase in inflammatory cells in cornea of PRK compared to flap-free EPI-LASIK,(t=10.32,P<0.01).5,The apoptosis cells of corneal stroma: In low cutting group, There was no significant difference in apoptosis cells in the corneal stroma between PRK and flap-free EPI-LASIK(t=2.45,P>0.05).But in high cutting group, There was a significant increase in apoptosis cells in corneal stroma of PRK compared to flap-free EPI-LASIK(t=6.03,P<0.01).6,The expression of bFGF and NF-κB in cornea: There was a increase in expression of bFGF and NF-κB in cornea in PRK and flap-free EPI-LASIK compared to control group. In low cutting group, There was no significant difference in the expression of bFGF and NF-κB in the corneal stroma between PRK and flap-free EPI-LASIK(t=2.55,t=2.13,t=1.02,t=2.22,P>0.05).But in high cutting group, compared to PRK, the expression of bFGF in flap-free EPI-LASIK was increased, while the expression of NF-κB was decreased(P<0.01).Conclusion Flap-free EPI-LASIK make flap with microkeratome and removal, basement membrane integrity, It can resist tear and damaged cells release various factors, make the postoperative corneal epithelium soon healed, inflammatory reaction light, especially in high cutting group, flap-free EPI-LASIK has a great advantage than PRK.