title: Effect of Laser in Situ Keratomileusis on Schiøtz, Goldmann, and Dynamic Contour Tonometric Measurements.
abstract: OBJECTIVE
  To assess the effect of laser in situ keratomileusis (LASIK) on ocular rigidity and compare its effect on intraocular pressure (IOP) readings with Goldmann applanation tonometry (GAT), Schiøtz indentation tonometry (ST), and dynamic contour tonometry (DCT).
  
  
  METHODS
  Prospective, observational, single-masked study. Eighty-one patients who underwent myopic LASIK and 108 unoperated myopic control patients were included in the study. The IOP was measured using GAT, DCT, and ST. The coefficient of ocular rigidity (Ko) was obtained from the regression analysis of the 3 readings obtained with each weight of the ST. Linear multiple regression analysis was performed with dummy variables to assess the effects of age, central corneal thickness (CCT), and refractive surgery on measured IOP values.
  
  
  RESULTS
  Age, CCT, and previous LASIK explained 39.41% of the IOP readings with GAT, 25.31% with DCT, and 3.28% with ST. LASIK caused a mean decrease of -2.51 mm Hg in IOP readings (P=0.000) with GAT, -1.29 mm Hg (P=0.036) with DCT, and no significant change in IOP readings with ST (P=0.299). Significant differences in the Ko were observed between the LASIK and control groups. The Ko values were unrelated to age and CCT in the LASIK and control groups.
  
  
  CONCLUSIONS
  ST seems to be less affected by previous LASIK procedures. There is a difference in the ocular rigidity between the unoperated and LASIK eyes that is not correlated with the CCT. Therefore, ST seems to measure changes in the biomechanical behavior of corneas that underwent LASIK surgery.
authors.affiliation: *Ramón y Cajal Universitary Hospital †Novovision ‡Rey Juan Carlos Universitary Hospital, Móstoles ¶Príncipe de Asturias Universitary Hospital **University of Alcalá, Madrid §Department of Optics, Pharmacology and Anatomy, University of Alicante ∥Foundation for the Visual Quality, Alicante, Spain #3rd University Department of Ophthalmology, Aristotle University, Thessaloniki, Greece.
authors.forename: Marco
authors.initials: M
authors.lastname: Sales-Sanz
authors.forename: Esther
authors.initials: E
authors.lastname: Arranz-Marquez
authors.forename: David P
authors.initials: DP
authors.lastname: Piñero
authors.forename: Carolina
authors.initials: C
authors.lastname: Arruabarrena
authors.forename: Dimitrios G
authors.initials: DG
authors.lastname: Mikropoulos
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Teus
mesh_terms: D000328:Adult; D000368:Aged; D003315:Cornea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D011446:Prospective Studies; D016037:Single-Blind Method; D014065:Tonometry, Ocular / Q000295:instrumentation* / Q000379:methods; D055815:Young Adult