The Experimental Research Of Femtosecond Laser Lenticule Transplantation And Clinical Study On Corneal Aberrations Of Fs LASIK

Part Ⅰ Histologic Observation of Femtosecond Laser Double Scanning and Tissue Removing in the Rabbit CorneaObjective:To evaluate the feasibility of femtosecond laser double scanning, and to study the relative histologic characters after corneal tissue removing.Methods:15New Zealand pure white rabbits randomly divided into groups named by femtosecond laster devices used which were Visumax, LDV and Intralase. Of every rabbit, one eye underwent femtosecond laser double scanning and tissue removing while the other eye was as self normal control. The treated corneal tissues were observed at1day,10days,1month,3months and6months after the surgery respectively, using slit-lamp, in vivo confocal microscopy, HE staining light microscope and transmission electron microscope (TEM).Results:VisuMax group could form a stroma lens after femtosecond laser scanning, which could better correspond to tissues nearby with slim edge. While, the other two groups could form a lamellar stroma layer after femtosecond laser scanning, the shape of the layers in this two groups were similar, which may cause obvious inner space under the corneal flap. The pathologic character postoperative was from edema to detumescence for corneal tissue, from clearness to blur for the healing line, from activity to silence for the cell, from disorder to regulation for extracellular stroma and from tiny bud to long branch for the corneal nerve.Conclusions:The femtosecond laser double scanning and tissue removing was feasible, of the three femtosecond laser VisuMax could create a lens. The tissue healing process postoperative was light, and the nerve repair need a period of time. Part Ⅱ Experimental Study on Femtosecond Laser Lenticule Transplantation in the Rabbit CorneaObjective:To evaluate the feasibility of VisuMax Femtosecond Laser induced Lenticule Transplantation in the rabbit cornea, and to observe the relative histologic characters of the corneal tissues after transplantation.Methods:10New Zealand pure white rabbits underwent the VisuMax femtosecond laser surgical procedure. For every rabbit, the right eye was performed femtosecond laser small incision lenticule extraction (SMILE), while the left eye was performed femtosecond laser corneal lenticule transplantation. The treated corneal tissues were observed at1day,10days,1month,3months and6months after the surgery respectively, using slit-lamp, in vivo confocal microscopy, HE staining light microscope and transmission electron microscope (TEM).Results:In the early stage, the pathologic response of the femtosecond laser corneal lenticule transplantation is relatively severe. The pathologic character postoperative was from edema to detumescence for corneal tissue, from clearness to blur for the boundary line grafts and bed, from activity to silence for the cell, from disorder to regulation for extracellular stroma and from tiny bud to long branch for the cornel nerve.Conclusions:The femtosecond laser lenticule transplantation was feasible, the lenticule can survive and merge together with recipient’s stroma. It needs at least half a year that the nerve repair to a relative stable state. Part Ⅲ Clinic Study on Corneal Aberrations of FS-LASIKObjective:To evaluate the changes in anterior and posterior corneal higher order aberrations after laser in situ keratomileusis LASIK)with different femtosecond lasers.Methods:A prospective case series study was conducted. Fs-LASIK and follow-up datas were collected by three refractive centers. In terms of voluntary accept fs-LASIK and underwent strict examinations for indications of preoperative patients, age18to45, refractive status for myopia or myopic astigmatism, sphere within (including)-9.00DS, cylinder within (including)-3.00DC. In total109samples (207eyes),32male (62eyes) and77female (145eyes). Patients were separated into3groups named by the device used:Visumax group(VL), LDV(DL) and Intralase (IL). Vision acuity, refractive status and the three-dimensional corneal topography was obtained preoperatively and postoperatively. Values of root mean square(RMS), higher order aberrations (HOA), coma and spherical aberration both in the anterior and posterior corneal surface were calculated with the pupil diameter of5.5mm.Results:1. There were no severe complications in all patients during and after surgery.2. Vision Acuity:Six months after surgery UCVA was1.17±0.17in VL group,1.17±0.16in DL group,1.25±0.20in IL group. There were significantly improvements compare with BCVA before surgery in each group(P<0.05), and there was no statistical difference between the groups (P>0.05).3.Refractive status:All groups made a full correct of myopia after surgery. Six months after surgery SE was-0.05±0.26in VL group,-0.02±0.18in DL group,-0.03±0.16in IL group. There was no statistical difference between the groups (P>0.05).4. Corneal aberrations:Six months after surgery the front surface RMS wasl.98±0.57, HOA was0.66±0.23, coma was0.41±0.24, Sph. A was0.40±0.18in VL group; the front surface RMS was1.90±0.79, HOA was0.67±0.32, coma was0.50±0.25, Sph. A was-0.50±0.28in DL group; the front surface RMS was0.30±0.06, HOA was0.29±0.07, coma was0.05±0.01, Sph. A was0.70±0.11in IL group. All datas increased significantly compare with datas preoperative (P<0.05) but for the RMS values and coma values in IL group.Conclusions:The aberration changes in anterior and posterior cornea in half year is fluctuation, the posterior corneal aberration does not change significantly. The aberration changes in anterior and posterior cornea performed by VisuMax femtosecond laser were in accordance with changes performed by LDV femtosecond laser.