title: Agreement among three types of spectral-domain optical coherent tomography instruments in measuring parapapillary retinal nerve fibre layer thickness.
abstract: OBJECTIVE
  To evaluate the agreement of parapapillary retinal nerve fibre layer (RNFL) thickness among three spectral-domain optical coherence tomography (OCT) instruments.
  
  
  METHODS
  Two hundred and three glaucomatous eyes and 88 normal eyes were imaged by Cirrus, RTVue and 3D OCT. The average and the four quadrant RNFL thicknesses were evaluated. Agreement among RNFL measurements was evaluated using Bland-Altman analysis and linear regression analysis. The percentage of each quadrant in the average RNFL thickness value was compared among the three instruments.
  
  
  RESULTS
  Cirrus showed significantly smaller thickness values than RTVue (difference=8.8 μm, p<0.0001) and 3D OCT (difference=8.1 μm, p<0.0001). Although RNFL measurements among the instruments were highly correlated, the Bland-Altman analysis revealed proportional biases for most of the pair-wise agreements. Additionally, 3D OCT showed strong proportional biases with RTVue and 3D OCT. RTVue had a smaller occupied proportion of nasal quadrants (30.2%) and a larger proportion of inferior quadrants (32.4%) compared with Cirrus and 3D OCT.
  
  
  CONCLUSIONS
  RNFL measurements among the instruments were well correlated but had different values for thickness. The measurement circle of RTVue might be more superior-temporally located compared with the other instruments. Differences in the measurement protocols might be affected by the disagreements. These instruments should not be used interchangeably.
authors.affiliation: Department of Surgery, Division of Ophthalmology, Kobe University Graduate School of Medicine, Kobe, Japan. kanaaki@med.kobe-u.ac.jp
authors.forename: Akiyasu
authors.initials: A
authors.lastname: Kanamori
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakamura
authors.forename: Mari
authors.initials: M
authors.lastname: Tomioka
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kawaka
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamada
authors.forename: Akira
authors.initials: A
authors.lastname: Negi
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000295:instrumentation*; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult