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.

The aim of this study was to evaluate the corneal reinnervation at the cap margin after SMILE.

The clinical data of 32 myopic eyes of 16 patients who received SMILE incision lenticule extraction surgerv 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.

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.

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.

Corneal reinnervation; Cornea surgery, laser; Lasers, excimer/therapeutic use; Microscopy, confocal; Nerve regeneration/physiology; Ophthalmic nerve/physiology; Surgical flaps; Small incision lenticule extraction