Abstract
PurposeTo characterize the early ocular-surface changes or tear inflammatory-mediators levels following small-incision lenticule extraction (ReLEx smile) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).MethodsForty-seven myopic subjects were recruited for this prospective study. Fifteen underwent ReLEx smile and thirty-two underwent FS-LASIK. Corneal fluorescein (FL) staining, tear break-up time (TBUT), Schirmer I test (SIT), ocular surface disease index (OSDI) and central corneal sensitivity were evaluated in all participants. Tears were collected and analyzed for interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nerve growth factor (NGF) and intercellular adhesion molecule-1 (ICAM-1) levels using multiplex magnetic beads. All measurements were preformed preoperatively and 1 day, 1 week, 1 month and 3 months postoperatively.ResultsFL scores in ReLEx smile group were lower than those of FS-LASIK group 1 week postoperatively (P = 0.010). Compared to the FS-LASIK group, longer TBUT were observed in ReLEx smile group 1 month (P = 0.029) and 3 months (P = 0.045) postoperatively. No significant differences were found in tear secretion for the two groups (P>0.05). OSDI scores were higher in FS-LASIK group 1 month after surgery (P = 0.020). Higher central corneal sensitivity was observed in ReLEx smile group 1 week, 1 month and 3 months (P<0.05) postoperatively. Compared to FS-LASIK group, lower and faster recovery of IL-6 and NGF levels in tears was observed in ReLEx smile group postoperatively (P<0.05). Tears TNF-α and ICAM-1 concentrations were not significantly different between the two groups at any follow-up time (P>0.05). Moreover, IL-6 and NGF levels correlated with ocular surface changes after ReLEx smile or FS-LASIK.ConclusionsIn the early postoperative period, ReLEx smile results in milder ocular surface changes than FS-LASIK. Furthermore, the tear inflammatory mediators IL-6 and NGF may play a crucial role in the ocular surface healing process following ReLEx smile and FS-LASIK.
Highlights
The femtosecond laser, which is characterized by its outstanding cutting precision and less-severe complications, has been widely applied in laser-assisted in situ keratomileusis (LASIK) [1,2,3]
Patients in refractive lenticule extraction (ReLEx) smile and FS-LASIK groups were matched in terms of age, initial uncorrected visual acuity, best spectacle-corrected visual acuity, mean spherical equivalent, central corneal thickness and corneal curvature (P.0.05)
For corneal FL staining, the scores in both ReLEx smile and FSLASIK groups increased significantly at postoperative 1 day compared with preoperative values (P,0.017)
Summary
The femtosecond laser, which is characterized by its outstanding cutting precision and less-severe complications, has been widely applied in laser-assisted in situ keratomileusis (LASIK) [1,2,3] This technique, known as femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), involves flap creation and stromal ablation using femtosecond laser and excimer laser, respectively. Ocular surface damage due to flap formation and stromal ablation is associated with post-LASIK dry-eye and other rare complications such as epithelial ingrowth and myopia regression [10,11,12,13,14]. Ocular surface damages occurring during refractive surgeries stimulate low or mild inflammation and increase the levels of tear inflammatory mediators (including cytokines, chemokines and growth factors) during early postoperative period. Epithelial cells and keratocytes express the receptors for tear inflammatory mediators, which are proposed to be involved in the corneal wound-healing process and responsible for post-LASIK complications [18,19,20]
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