Effect Of Insulin-like Growth Factor-1on Corneal Surface Ultrastructure And Nerve Regeneration Of Rabbit Eyes After Laser In Situ Keratomileusis

Objective To explore the effect of insulin-like growth factor-1(IGF-1)on corneal surface ultrastructure and nerve regeneration in rabbit modelsafter laser in situ keratomileusis (LASIK).Methods Forty-two healthy New Zealand white rabbits (84eyes intotal) were performed laser in situ keratomileusis. The left eyes weretreated with IGF-1eye drops6times a day as treatment group, and the righteyes were treated with normal saline (NS) as control group. The parametersof dry eye including Schirmer I test and tear break-up time were examinedat1d,1w,2w,1m,3m and6m after surgery. The corneal surfaceultrastructure of two rabbits was observed by transmission electronmicroscopy and the nerve regeneration of five rabbits was evaluated bycounting the new regenerated nerves at different time points in two groups.At6m after surgery, the corneas were used to observe the histologicalstructure in two groups.Results1. TEM: At1d after surgery, the density of corneal epithelial microvilli was significantly reduced and the microvilli lost their regularity,and the vacuole was observed in the corneal stromal layer. At1w aftersurgery, the number of corneal surface microvilli obviously increased. At2w after surgery, the number of corneal epithelial microvilli approached thenormal level.2. Golden Chloride Staining: At1d after surgery, the nervefibers in the subepithelial and the superficial stroma in the laser ablationmostly disappeared, but there were not being destroyed in the hinge of theflap. At7d after LASIK surgery, new regenerated nerve fibers sproutedfrom the nerve at the edge of corneal flap. At6m after surgery, the densityand morphology of peripheral corneal nerve fiber network had beenreturned to the preoperative level, but the density in central cornea wassmaller than pre-operation. The number of regenerated nerve fibers in theIGF-1-treated group was higher than that in the NS-control group at alltime points (P<0.05).3. The parameters of dry eye showed that the values in thetreatment group were higher than that in the control group at all time pointsexcept the first day and6th month after LASIK.4. At6m after LASIK, the structure of rabbit cornea tissue wasnormal with HE staining, the cells of cornea arranged tightly and orderly.Conclusion1. IGF-1can effectively accelerate the repair of cornealsurface ultrastructure and corneal nerve regeneration of rabbit eyes after LASIK.2. IGF-1eye drops for local application can improves thedry eye symptoms.