ABSTRACT
Background Corneal reinnervation of subbasal nerve plexus have been found after small incision lenticule extraction(SMILE).However,there were few reports about corneal reinnervation mode and dynamic changes at the corneal cap in different time points postoperation.Objective The aim of this study was to evaluate the corneal reinnervation at the cap margin after SMILE.Methods The clinical data of 32 myopic eyes of 16 patients who received SMILE incision lenticule extraction surgery in Affiliated Eye Hospital of Shandong Medical College from April 2014 to April 2015 were retrospectively analyzed.The following-up was carried in 1 week,1 month,3 months and 6 months after surgery,and in-vivo confocal microscopy was used to acquire images of the central corneal subbasal nerve plexus before and after surgery,with the scan range of 0.4 mm×0.4 mm,from which nerve density and nerve tortuosity were evaluated using Image-Pro Plus imaging analysis software.The overall length of nerve fibers at the central cornea was measured to assess the subbasal nerve density,and the repair of nerve fibers at cap was observed.Results The corneal subbasal nerve density was (19 687.45 ± 1 147.59),(10 500.46 ± 1 056.22),(12 833.40-± 1 047.98),(13 564.04-± 1 173.01) and (14 661.35-±941.92) μm/mm2 in preoperation and postoperative 1 week,1 month,3 months,6 months,respectively,with a significant difference among different time points (F =319.44,P=0.000),and the corneal subbasal nerve densitis in postoperative time points were significantly reduced in comparison with the preoperation,and corneal subbasal nerve densities were gradually increased after surgery as the extending of time,showing significant differences between different time points (all at P＜ 0.01).Abundant corneal subbasal nerve fibers were seen with the near normal morphology after surgery.However,the fragments and disaggregation of nerve fibers were found at the incision of cap margins,and some nerve fibers extended toward the inner cap at the non-incision of cap margins 1 week after surgery.In 3-6 months after SMILE,the continuous extension of nerve fibers was exhibited under the confocal microscope.Conclusions Six months after surgery,less invasive SMILE technique can remain the superficial corneal nerve fibers.Corneal innervation shows a radiate mode from peripheral cornea outside toward inside of the cap.The subbasal never fiber density is gradually increased with the extending of time after SMILE.
ABSTRACT
Background To understand the distribution and development of corneal nerve in animal or human has an important significance for clinical and basic research of corneal diseases.At present,some studies on cornea nerve development and location have been performed.However,the quantified study on innervation and distribution of corneal nerve fibers as embryonic development has not been reported.Objective This study attempted to understand the distribution of corneal nerve fibers in the development of chick embryo,and to evaluate the changes of the length and density of corneal nerve fibers with aging of chick embryo.Methods Whole chick corneas with limbus were obtained from chick embryo aged 6-20 days (E6-E20),and corneal nerve fiber was labeled using immunofluorescence technique by anti-neuron-specific β-Ⅲ tubulin antibody.The corneas were radially cut into 4 parts,and the integrate corneal flat mounts were prepared with the upward epithelium and mounting with anti-fade fluorescent quenching buffer glycerin containing DAPI.Fluorescence microscope was used to capture the nerve fiber images in cornea,and cornea area and the number of nerve fiber bundles were exhibited by using Photoshop CS4.Cornea nerve fiber density and total length were measured by Imaris x64 7.4.2 software.Results Total cornea flat mounts showed that the nerve bundles grew from temporal scleral forward cornea limbus at E6-E8,and the nerve fibers formed the ring surrounding by limbus during E9-E10.Then the fibers extended forward the central cornea in E11 to E15 and developed into nerve fiber plexus on the whole cornea in E16 to E20.During the period of E6-E20,the corneal surface area,the length and density of corneal nerve fibers were gradually increased with the aging of chick embryo,showing statistically significant differences among different time points (F =127.007,227.051,67.748,all at P＜0.01).The increase of the corneal area of the chick embryo presented a strong positive correlation with the extending of length of the corneal nerve fiber (r =0.863,P＜0.01).Chick corneal nerve fiber bundle appeared at E13,with a number of (59.00 ± 1.14)/mm2 and then increased to a peak of (576.75 ±29.16)/mm2 at E 18 and reduced to (299.67± 25.46)/mm2 at E20,with a significant difference among them (F =13.759,P=0.000).Conclusions Corneal nerve starts to develop in E9 of chick embryo,and the corneal surface area,the total length of the corneal nerve fibers and the density rapidly increase concurrently with the development of chick embryo.