title: Tonometry after laser in situ keratomileusis treatment: a preliminary study in Thai patients.
abstract: OBJECTIVE
  To evaluate the change in intraocular pressure (IOP) measurement by Goldmann applanation tonometer after Laser in Situ Keratomileusis (LASIK) for myopia and myopic astigmatism, and to assess the correlation between the changes of lOP reading and the reduction of central corneal thickness (CCT) after LASIK in Thai patients.
  
  
  METHODS
  Prospective correlational study.
  
  
  METHODS
  LASIK was performed on 65 eyes of 33 patients for correction of myopia and myopic astigmatism. IOP was measured by Goldmann applanation tonometer before and 3 months after LASIK. The correlation between the change in IOP reading and the change in central corneal thickness were evaluated.
  
  
  RESULTS
  IOP reading was significantly reduced by mean of 2.9 +/- 2.5 mmHg (p = 0.0001). The authors used Pearson analysis to study the correlation between the change in IOP and the reduction of CCT. In subgroup analysis the patients were divided by degree of myopia: group 1, myopia less than -3 diopters (D) (n = 14); group 2, myopia -3 to -6 D (n = 31); group 3, myopia greater than -6 D (n = 20)). The result showed more correlation in higher myopia group (Pearson; r = 0.158 in group 3, r = -0.098 in group 2 and r = -0.102 in group 1).
  
  
  CONCLUSIONS
  Goldmann applanation tonometry underestimates the IOP in thin cornea. Variability in CCT is a potent confounder of this tonometry technique. Therefore, it has important implications for considering CCT measurement incorporated with Goldmann applanation tonometry for glaucoma diagnosis especially in myopic patients who undergo LASIK surgery.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. sinrv@mahidol.ac.th
authors.forename: Ngamkae
authors.initials: N
authors.lastname: Ruangvaravate
authors.forename: Atiporn
authors.initials: A
authors.lastname: Thuangtong
authors.forename: Panida
authors.initials: P
authors.lastname: Kosrirukvongs
authors.forename: Pinnita
authors.initials: P
authors.lastname: Prabhasawat
authors.forename: Wipawee
authors.initials: W
authors.lastname: Booranapong
authors.forename: Sabong
authors.initials: S
authors.lastname: Srivannaboon
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000150:complications / Q000601:surgery*; D001837:Body Weights and Measures; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D020731:Keratomileusis, Laser In Situ; D008297:Male; D009216:Myopia / Q000150:complications / Q000601:surgery*; D011446:Prospective Studies; D013785:Thailand; D014065:Tonometry, Ocular / Q000379:methods*