title: Measurement of Central Corneal Thickness Using Ultrasound Pachymetry and Orbscan II in Normal Eyes.
abstract: OBJECTIVE
  To compare ultrasound pachymetry and Orbscan II for measurement of central corneal thickness (CCT) in normal eyes.
  
  
  METHODS
  The current study was performed at Labbafinejad Medical Center (LMC), Tehran, Iran. Three hundred eyes from 150 healthy individuals referred for keratorefractive surgery were assessed first by Orbscan II and then by ultrasound pachymetry, and CCT values were recorded and compared.
  
  
  RESULTS
  Overall, Orbscan II overestimated CCT as compared to ultrasound pachymetry by about 2.4% (mean values 547.6 ± 34.7 versus 534.8 ± 34.7, respectively, P < 0.001). The difference was more significant when CCT was less than 500 microns (mean values 493.2 ± 16.9 versus 479.9 ± 15.6, mean overestimation: 2.6%, P < 0.001). There was good linear correlation between the two methods (Pearson's correlation r = 0.968, P < 0.0001).
  
  
  CONCLUSIONS
  Orbscan II has good correlation with ultrasound pachymetry for measurement of CCT in normal eyes; however Orbscan II should not be used to evaluate corneal thickness before keratorefractive surgeries, as it tends to overestimate corneal thickness and may result in undesirable, low residual stromal thickness.
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Sadoughi
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Bahram
authors.initials: B
authors.lastname: Einollahi
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Einollahi
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Rezaei
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Danial
authors.initials: D
authors.lastname: Roshandel
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Sepehr
authors.initials: S
authors.lastname: Feizi
keywords: Central Corneal Thickness; Orbscan II; Ultrasound Pachymetry