title: Evaluation of the tear film stability after laser in situ keratomileusis using the tear film stability analysis system.
abstract: OBJECTIVE
  To evaluate the tear film stability of patients before and after laser in situ keratomileusis (LASIK) using the tear film stability analysis system (TSAS).
  
  
  METHODS
  Prospective observational case series.
  
  
  METHODS
  New videokeratography software for a topographic modeling system (TMS-2N) was developed that can automatically capture consecutive corneal surface images every second for 10 seconds. Thirty-four subjects (64 eyes) who underwent myopia LASIK were enrolled in this study. All subjects were examined with the new system before LASIK and at 1 week, 1 month, 3 months, and 6 months after the surgery. Corneal topographs were analyzed for tear breakup time (TMS breakup time) and breakup area (TMS breakup area). Based on pre-LASIK TSAS analysis, subjects were separated into normal and abnormal TSAS value groups. The criteria for the normal group were either TMS breakup time more than 5 seconds or TMS breakup area less than 0.2. The percentage of the occurrence of superficial punctuate keratitis was compared between the two groups with regard to subject's dry eye signs and symptoms.
  
  
  RESULTS
  Tear film stability decreased significantly during the early period after LASIK, as indexed by decreased TMS breakup time and increased TMS breakup area. Tear film instability resolved at 6 months after surgery. Before LASIK, 22 subjects (43 eyes) had normal TSAS evaluation and 12 subjects (21 eyes) were abnormal. After LASIK, among normal TSAS value eyes, 8 of 43 (18.6%) eyes developed superficial punctuate keratitis. In sharp contrast, 14 of 21 (66.7%) eyes in the abnormal group displayed superficial punctuate keratitis, correlating well with the patients' dry eye symptoms. The difference in the presence of superficial punctuate keratitis after LASIK between normal and abnormal TSAS value groups was statistically significant (P <.001). Subjects with abnormal TSAS evaluation also displayed resistance to dry eye treatment and had extended period of recovery.
  
  
  CONCLUSIONS
  Tear film stability analysis can be a useful means for screening LASIK candidates before surgery and for prognosticating dry eye symptoms thereafter.
authors.affiliation: Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan. xzheng@m.ehime-u.ac.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Goto
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zheng
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Klyce
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kataoka
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Uno
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Mike
authors.initials: M
authors.lastname: Karon
authors.forename: Sumie
authors.initials: S
authors.lastname: Hirano
authors.forename: Shigeki
authors.initials: S
authors.lastname: Okamoto
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D000328:Adult; D003315:Cornea / Q000378:metabolism* / Q000601:surgery; D019781:Corneal Topography / Q000379:methods*; D015352:Dry Eye Syndromes / Q000175:diagnosis; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D007765:Lacrimal Apparatus / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000378:metabolism* / Q000601:surgery; D011446:Prospective Studies; D013666:Tears / Q000378:metabolism*