title: [The correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK].
abstract: OBJECTIVE
  To investigate the correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK (FS-LASIK) surgery.
  
  
  METHODS
  In this prospective clinical study, 31 patients undergoing FS-LASIK for myopia were recruited. The upper and lower tear meniscus volumes (UTMV and LTMV) were measured by customized anterior segment optical coherence tomography, tear film osmolarity was measured by a TearLab Osmolarity test device, central corneal sensation was measured by a Cochet-Bonner esthesiometer preoperatively, at 1 week, 1 and 3 months postoperatively. Repeated measures analysis of variance was used to evaluate whether the tear film osmolarity, tear meniscus volume, and corneal sensation were changed after surgery. The correlations between these variables were analyzed by the Pearson correlation analysis.
  
  
  RESULTS
  The tear film osmolarity was (310.03 ± 16.48) mOsms/L preoperatively, (323.51 ± 15.92) mOsms/L at 1 week, (319.93 ± 14.27) mOsms/L at 1 month, and (314.97±12.91) mOsms/L at 3 months. The UTMV was (0.42±0.15), (0.25± 0.09), (0.30±0.11), and (0.35±0.09) μL, respectively; the LTMV was (0.60±0.21),(0.37±0.08), (0.44± 0.14), and (0.52±0.17) μL, respectively. The tear film osmolarity was significantly higher at 1 week and 1 month postoperatively compared with the baseline (P=0.001, 0.004), and reduced to the preoperative level at 3 months (P=0.573). The UTMV, LTMV, and corneal sensation values presented significant decreases at all postoperative time points (all P<0.05). The Pearson correlation analysis showed the postoperative UTMV had a weak relationship with corneal sensation at 1 week after surgery (r=0.356,P=0.005). There were significant correlations between the preoperative LTMV and corneal sensation at 1 week, 1 and 3 months (respectively, r=0.422, 0.366, 0.352;P=0.001, 0.004, 0.006). No significant correlations were found between the tear film osmolarity, tear meniscus volume, and corneal sensation after surgery (all P>0.05).
  
  
  CONCLUSIONS
  The tear film osmolarity, tear meniscus volume, and corneal sensation became aggravated due to the FS-LASIK surgery procedures. There were significant correlations between the preoperative tear meniscus volume and recovery of corneal sensation early after surgery. A higher tear meniscus volume before surgery may contribute to a faster corneal sensation recovery.
authors.affiliation: Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China.
authors.forename: Luyan
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiyu
authors.initials: X
authors.lastname: Sun
authors.forename: Ye
authors.initials: Y
authors.lastname: Yu
authors.forename: Yan
authors.initials: Y
authors.lastname: Xiong
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Cui
authors.forename: Qinmei
authors.initials: Q
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Hu
mesh_terms: D000704:Analysis of Variance; D003315:Cornea / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D009994:Osmolar Concentration; D011184:Postoperative Period; D011446:Prospective Studies; D012677:Sensation; D013666:Tears / Q000737:chemistry; D041623:Tomography, Optical Coherence