Effect Of Leukemia Inhibitory Factor On Corneal Nerve Regeneration Of Rabbit Eyes After Laser In Situ Keratomileusis

Objective To explore the effects of leukemia inhibitory factor on corneal nerve regeneration of rabbit eyes after laser in situ keratomileusis and the security of LIF eye drops.Methods Forty healthy New Zealand rabbits were taken as experimental subjects and 5 of them were used as blank control group to observe the morphology of normal corneal nerve. Laser in situ keratomileusis for myopia was performed on eyes of the rest 35 rabbits (70 eyes in total) and then 1μg/mlLIF eye drops were used 4 times a day on the left eyes as treatment group, and a balanced salt solution was used on the right eyes as control group. The parameters for dry eye were examined on the 1st day, 1st week, 2nd week, 1st month, 3rd month, and 6th month respectively after the operation, and then 5 rabbits of each group were sacrificed so as to remove their corneas for golden chloride staining. The effect of LIF on corneal nerve regeneration was observed by optical microscopy and the results of two groups, at the same time, were compared. The other 5 rabbits were sacrificed on the 6th month and the corneas were cut into 2 pieces averagely. One piece was used to observe the histological structure of cornea with HE staining, and the other was used to observe the microstructure of cornea by transmission electron microscopy.Results 1.Nerve fibers in the subepithelial and the shallow stroma located at the cutting area mostly disappeared after LASIK surgery. However, the nerve fibers in the hinge of the flap were not destroyed. New regenerated nerve fibers were found at the edge of corneal flap on the 7th day after LASIK. At the time of the 6th month, the number and morphology of the corneal nerves in the subepithelial and the shallow stromal were approximately normal. In addition, the density of nerve fibers in the peripheral cornea showed complete recovery (no significant difference). However, the density in the central cornea was still lower than those before LASIK surgery.2. The number of repaired nerve fibers of treatment group was higher than control group except the time of the 6th month (P﹤0.05).3. Parameters for dry eye between two groups were compared at each postoperative time point and the result showed LIF group was significantly higher than BSS group at the 2nd week, 1st month and 3rd month respectively.4. There was no corneal new blood, epithelium exfoliation, lens opacities during 6 months with treatment of LIF. The structure of rabbit cornea tissue under light microscopy and transmission electron microscopy also had no change. Conclusion 1.The corneal nerves were damaged mostly after LASIK surgery. Nerve fibers in the subepithelial and the shallow stromal located at the cutting area disappeared after LASIK surgery. However, the nerve fibers in the hinge of the flap were not damaged.2. Leukemia inhibitory factor can effectively advance corneal nerve regeneration of rabbit eyes after LASIK. LIF eye drop was safe for the treatment of rabbit eyes after LASIK surgery.