The Histological Changes Of Corneal Tissue Via Confocal Microscope Observation After Femtosecond Laser Of LASIK

Objective To observed the central corneal thickness and kinetic morphological changes of keratocytes and corneal nerve in corneal flap after femtosecond laser in situ keratomileusis (LASIK).Method Sixty eyes of30patients with refractive error were performed femtosecond laser manufacture corneal flap of LASIK surgery with both femtosecond laser system and excimer lasertreatment system. All patients stop wearing contact lenses for more than two weeks, and no other eye diseases or a history of surgical, and no serious systemic systemic disease. Femtosecond laser pulse frequency of200kHz and a pulse energy of100to150nJ, corneal flap diameter of7.9to8.3mm, the flap position of0°, the flap edge angle of90°, expected manufacturing flap thickness of100μm. All operations were performed by the same surgery doctor, examination the central corneal flap thickness3months postoperatively application of OCT. The morphology of keratocytes and corneal nerve wereobserved with confocal microscope1week,1month,3months after laser surgery, respectively.Results To three months after operation, all eyes UCVA achieves preoperative BCVA. No haze or flap folds were observed by slit lamp examination through the observation duration.3months postoperatively application of OCT to measure the central corneal flap thickness was (103.13±8.97)μm. Statistical analysis shows t=1.91, P=0.07, the difference was not statistically significant, indicating that the femtosecond laser corneal flap has good accuracy and predictability. Different periods after surgery to check all eye surgery, granular, lumpy or irregular-shaped high reflective particles were present in anterior corneal stroma. One week after surgery,42(70%) at the interface of the corneal flap corneal stromal cells expressed as a mild activation status, with time, activated stromal cells gradually reduced, but3months after surgery there are still seven eyes (12%) wered observed mild activation state. Cell reflective mitigate than before, and the cell activation reaction reduced than before. One week after surgery seven eyes(12%) were observed independent, short (<50μm), curved subbasal nerve fibers,48eyes (80%) were seen curved filamentous nerve fibers a month after surgery. The subbasal nerve of27eyes (45%) which nerve fiber length>200μm and classes beaded structure were appear at three month postoperative obzervation, while still with preoperative subbasal nerve fibers from some differences. One week after the operation46eyes (77%) could be seen filaments or discontinuous nerve fibers at the "interface",49eyes (82%) were visible long nerve fibers or filamentous nerves arounded the terminal or pheripheral of nerve fibers a month after surgery,57eyes (95%) were visible long nerve fibers or filaments of nerve fibers three months after the surgery.Conclunsions The UBVA of patients who experienced Femtosecond LASIK can reach to the BCVA3month after surgery. Compared central corneal flap thickness after3months with pre-set corneal flap thickness there was no statistically significant differences. Femtosecond LASIK can cause cellular level reaction. Repair of corneal nerve fiber morphology with the extension of time gradually close to preoperative form, but there are still morphological differences with preoperative3months after surgery.