title: Reproducibility and repeatability of central corneal thickness measurement in healthy eyes using four different optical devices.
abstract: OBJECTIVE
  The aim of the study is to compare the measurements of central corneal thickness (CCT) performed by two examiners with four different methods at different times inter- and intra-individually.
  
  
  METHODS
  Thirty healthy people were included in the study. In these measurements, an optical low-coherence reflectometry (OLCR), an optic coherence tomography (OCT), a specular microscopy (SM), and a corneal topography (CT) were used. Two examiners performed the measurements in a consecutive manner. After 1-7 days of the first measurements, the second measurements were performed again consecutively. The mean of three measurements was taken in each session for all devices.
  
  
  RESULTS
  In OCT measurements, there was a significant difference between two examiners in both sessions (p < 0.001), while no significant differences were found between two examiners in first and second sessions in SM, CT, and OLCR measurements. When each examiner's measurements were compared to two sessions, there were no significant differences (p > 0.05, for all) except the SM measurements of the first examiner (p = 0.041). When the first measurements of two examiners were compared, the smallest values were of OCT. At the first session of two examiners, there was a significant difference between OCT and CT measurements, and between OCT and OLCR (p < 0.001, p = 0.002 for the first examiner and p < 0.001 for the second examiner, respectively).
  
  
  CONCLUSIONS
  Our study showed that CCT measurements made by CT and OLCR methods were almost same and highly correlated for both the examiners' measurements. CCTs measured by OCT were on average 30 μm thinner than CT and OLCR.
authors.affiliation: Department of Ophthalmology, Istanbul Medeniyet University School of Medicine, Goztepe, Istanbul, Turkey. drrkaradag@yahoo.com.
authors.forename: Remzi
authors.initials: R
authors.lastname: Karadag
authors.affiliation: Department of Ophthalmology, Istanbul Medeniyet University Goztepe Research and Training Hospital, Goztepe, Istanbul, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Unluzeybek
authors.affiliation: Department of Ophthalmology, Istanbul Medeniyet University Goztepe Research and Training Hospital, Goztepe, Istanbul, Turkey.
authors.forename: Ozgur
authors.identifier: http://orcid.org/0000-0003-2839-2301
authors.initials: O
authors.lastname: Cakici
authors.affiliation: Department of Ophthalmology, Istanbul Medeniyet University Goztepe Research and Training Hospital, Goztepe, Istanbul, Turkey.
authors.forename: Ayse Yagmur
authors.initials: AY
authors.lastname: Kanra
authors.affiliation: Department of Ophthalmology, Istanbul Medeniyet University School of Medicine, Goztepe, Istanbul, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Bayramlar
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology*; D063171:Corneal Pachymetry / Q000295:instrumentation*; D019781:Corneal Topography / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009929:Organ Size; D012372:ROC Curve; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation*
keywords: Central corneal thickness; Corneal topography; Optic coherence tomography; Optical low-coherence reflectometry; Pachymetry; Specular microscopy