ABSTRACT
Background The ultrastructure change and growth of corneal nerve after laser in situ keratomileusis (LASIK) are some influent factors to the stability of tear film and the sensibility of cornea.Some relevant studies are lack up to now.Objective This study is to observe the changes of ultrastructure of corneal epithelium and regeneration of corneal nerve fiber.Methods LASIK was performed on the lateral eyes of 48 New Zealand white rabbits.Rabbit eyes were excavated at instant in postoperation,one day,seven days,one,three and six months after LASIK.Change of corneal ultrastructure and corneal nerve staining were examined under the scanning electron microscope (SEM) and transmmision electron microscope (TEM) at the time points mentioned above.The numbers of microvilli of corneal epithelial cells in different postoperative time were analyzed.10% AuCl was used to evaluate the growth status of corneal nerve in different time after LASIK.Results Irregularity of microvillus of corneal epithelial cells,degrease of cell density were seen under the TEM and some cavities could been observed in the instant of postoperation.The connection abnormality of intercells,dropsy and rupture of microvillus were presented under the SEM,However,the ultrastructure of corneal epithelial cells was almost normal in 7 days after LASIK.The numbers of microvillus in corneal epithelial cells were significantly declined in the postoperative instant group compared with preoperative group (P＜0.05),but no evidently difference was found in postoperative 1 day and 7 days groups compared with preoperative group(P＞0.05).Corneal nerve staining showed that in 1 day after surgery,nerve plexus was deprivation and boundary of nerve injury was clear and nerve fibers were cut off.After one month some reborn nerve fiber grew into the cornea flap.Reborn corneal nerve fiber can be seen at center laser ablation area after six months of LASIK.Conclusion The ultrastructure change of corneal epithelial cells in the early stage after operation may be a important factor causing dry eye symptom following LASIK.The growth fashion of corneal nerve fibers is from the cutting edge to the center of corneal flap.