title: Central corneal thickness measurements by ultrasound, Orbscan II, and Visante OCT after LASIK for myopia.
abstract: To compare central corneal thickness measurements obtained with Orbscan II scanning slit topography, Visante optical coherence tomography (OCT), and ultrasound pachymetry in myopic eyes after LASIK.
  
  
  
  This retrospective study included 34 consecutive patients (68 eyes) who underwent LASIK for the correction of myopia. Six months after surgery, central corneal thickness measurements were obtained using ultrasound pachymetry, Orbscan scanning slit topography, and Visante OCT. Data were analyzed using paired sample t test, Bland and Altman plot, and linear regression.
  
  
  
  Average postoperative central corneal thickness was 436.65+/-43.82 microm for ultrasound pachymetry, 422.84+/-51.04 microm for Orbscan (0.89 acoustic equivalent correction factor), and 422.26+/-42.46 microm for Visante. Compared to the ultrasound measurement, Orbscan and Visante measurements significantly underestimated the corneal thickness by 13.81+/-17.34 microm (P<.01) and 14.38+/-10.13 microm (P<.01), respectively.
  
  
  
  Both Orbscan and Visante OCT underestimated central corneal thickness compared to ultrasound pachymetry 6 months after LASIK, although measurements obtained with Visante OCT had better agreement and correlation with ultrasound pachymetry than with Orbscan.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Chinese University of Hong Kong, University Eye Center, Hong Kong Eye Hospital, Hong Kong. artcheng@netvigator.com
authors.forename: Arthur C K
authors.initials: AC
authors.lastname: Cheng
authors.forename: Srinivas K
authors.initials: SK
authors.lastname: Rao
authors.forename: Silvania
authors.initials: S
authors.lastname: Lau
authors.forename: Chris K S
authors.initials: CK
authors.lastname: Leung
authors.forename: Dennis S C
authors.initials: DS
authors.lastname: Lam
mesh_terms: D001699:Biometry; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography / Q000379:methods*; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D033401:Microscopy, Acoustic / Q000379:methods*; D009216:Myopia / Q000601:surgery*; D011184:Postoperative Period; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000379:methods*