title: Effect of mild to moderate myopic correction by laser-assisted in situ keratomileusis on intraocular pressure measurements with goldmann applanation tonometer, tono-pen, and pneumatonometer.
abstract: OBJECTIVE
  To evaluate the effect of mild to moderate myopic correction by laser-assisted in situ keratomileusis (LASIK) on intraocular pressure (IOP) measurements with three tonometers: the Goldmann applanation tonometer, Tono-Pen, and pneumatonometer.
  
  
  METHODS
  In a prospective study of a clinic-based population undergoing elective LASIK surgery for myopia correction, IOP measurements were obtained preoperatively and postoperatively with a Goldmann applanation tonometer, Tono-Pen, and pneumatonometer. Central corneal thickness and keratometric and astigmatism measurements were also obtained before and after surgery. A paired test was used to evaluate the significance of differences between preoperative and postoperative IOP measurements with each instrument. Linear regression was used to correlate IOP measurements with degree of myopia corrected, astigmatism, and central corneal thickness before and after surgery.
  
  
  RESULTS
  The study included 66 eyes of 34 individuals with a mean preoperative refractive error of -5.66 + 2.3 D (mean + SD). The reduction of central corneal thickness after LASIK of 0.032 + 0.030 mm (mean + SD) was statistically significant ( < 0.0001). However, there was no statistically significant change in mean IOP after the procedure with the Goldmann applanation tonometer or the Tono-Pen, while the pneumatonometer, was associated with a small but statistically significant decrease in mean IOP of 1.1 mm Hg.
  
  
  CONCLUSIONS
  In this group of patients with mild to moderate myopia, LASIK had little or no statistically significant influence on IOP readings obtained with a Goldmann applanation tonometer, Tono-Pen, or pneumatonometer. This finding is in contrast to earlier reports of greater amounts of myopic correction, in which significant reductions in measured IOP were observed. Further study is needed to determine whether a critical amount of corneal change after LASIK is required to have a significant effect on IOP measurements.
authors.affiliation: Department of Opthalmology and Visual Science, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: Roya
authors.initials: R
authors.lastname: Vakili
authors.forename: Saira A
authors.initials: SA
authors.lastname: Choudhri
authors.forename: Shachar
authors.initials: S
authors.lastname: Tauber
authors.forename: M Bruce
authors.initials: MB
authors.lastname: Shields
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D020731:Keratomileusis, Laser In Situ; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D013524:Surgical Flaps; D014065:Tonometry, Ocular / Q000379:methods*