[Comparison of corneal nerve regeneration and dry eye condition after conventional LASIK and femtosecond-assisted LASIK].
OBJECTIVE
To compare the regeneration of subbasal epithelial nerve plexus in the central cornea and dry eye condition between patients undergoing conventional LASIK surgery and femtosecond-assisted LASIK surgery.


METHODS
It was across-sectional study. Thirty patients (60 eyes) who had LASIK at our hospital from October 2011 to September 2012 were included in this study. Patients were divided into conventional LASIK group and femtosecond-assisted LASIK group based on the method used for corneal flap creation. Subjective and objective dry eye tests were carried out at 1 year after surgery. HRT III confocal microscopy was used to observe the regeneration of subbasal epithelial nerve plexus, and the images were analyzed by ACCMetrics software using quantitative parameters to determine the density and morphology of corneal nerve fibers. The data of corneal nerve fibers and dry eye condition in the two groups undergoing different LASIK procedures was compared using an independent sample t test.


RESULTS
During the one-year postoperative follow-up, the Schirmer test result, tear film break-up time value, and ocular surface disease index score in the F-LASIK group [(12.65 +/- 8.73) mm/5min, (7.85 +/- 2.81) s, (7.25 +/- 6.35) points] were not significantly different from that in the C-LASIK group [(6.73 +/- 10.55) mm/ 5 min, (8.77 +/- 3.04) s, (4.46 +/- 5.37) points] (t =1.399, -1.050, -1.613, P > 0.05). Regarding the nerve fiber measurements, which included corneal nerve fiber density, corneal nerve branch density, corneal nerve fiber length, corneal total branch node, corneal nerve fiber width, and corneal nerve fiber tortuosit, there was no statistically significant difference in their results between patients who had femtosecond-assisted LASIK surgery [(16.46 +/- 6.65 )/mm2, (19.27 +/- 9.56)/mm2, (10.88 +/- 4.70) mm/mm2, (65.10 +/- 38.43)/mm2, (4.76 +/- 0.34) microm, (2.30 +/- 0.34) grades] and those who had conventional LASIK surgery [(15.99 +/- 7.14)/mm2, (19.39 +/- 7.07)/mm2, (11.30 +/- 3.17) mm/mm2, (68.43 +/- 34.94)/mm2, (4.73 +/- 0.24) microm, (2.14 +/- 0.34) grades] (t = -0.229, 0.049, 0.365, 0.306, -0.394, -1.629, P > 0.05).


CONCLUSIONS
The difference between conventionalLASIK and femtosecond-assisted LASIK does not significantly affect the dry eye test values and nerve fiber measurements in patients at 1 year after LASIK.
Chenying
C
Yu
Ying
Y
Li
Zhonghai
Z
Wang
Yang
Y
Jiang
Yumei
Y
Jin
D003315:Cornea / Q000294:innervation*; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods; D018613:Microscopy, Confocal; D009412:Nerve Fibers / Q000473:pathology; D009416:Nerve Regeneration; D011184:Postoperative Period; D011446:Prospective Studies; D013524:Surgical Flaps; D013666:Tears / Q000502:physiology