title: Intrasession, intersession, and interexaminer variabilities of retinal nerve fiber layer measurements with spectral-domain OCT.
abstract: OBJECTIVE
  To evaluate the intrasession, intersession, and interexaminer variabilities of retinal nerve fiber layer measurements (RNFL) with spectral-domain optical coherence tomography (OCT).
  
  
  METHODS
  A total of 32 healthy individuals and 34 patients with chronic glaucoma underwent RNFL measurements with the Cirrus HD-OCT Model 4000 (Carl Zeiss Meditec, Dublin, CA, USA) 5 times during the same sitting by one examiner to assess intrasession variability. The same examiner performed RNFL measurements in the same patients on 5 different days to assess intersession variability. A second examiner performed RNFL measurements in the same patients to assess interexaminer variability. The coefficients of variation and intraclass correlation coefficients were obtained for the following parameters: average thickness, quadrant thickness, and Clock hour thickness measurements.
  
  
  RESULTS
  Intrasession variability: In patients with glaucoma, coefficients of variation ranged from 4.51% to 11.84%. Intraclass correlation coefficients ranged from 0.74 to 0.99. In healthy individuals, coefficients of variation ranged from 2.92% to 6.99%. Intraclass correlation coefficients ranged from 0.89 to 0.98. Intersession variability: In patients with glaucoma, coefficients of variation ranged from 3.68% to 10.50%. Intraclass correlation coefficients ranged from 0.82 to 0.99. In healthy individuals, coefficients of variation ranged from 3.13% to 6.92%. Intraclass correlation coefficients ranged from 0.87 to 0.99. Interexaminer variability: In patients with glaucoma, coefficients of variation ranged from 2.62% to 14.94%. Intraclass correlation coefficients ranged from 0.55 to 0.98. In healthy individuals, coefficients of variation ranged from 2.04% to 7.31%. Intraclass correlation coefficients ranged from 0.86 to 0.98.
  
  
  CONCLUSIONS
  These findings indicate that RNFL measurements with spectral-domain OCT display excellent reproducibility, with low intrasession, intersession, and interexaminer variabilities.
authors.affiliation: Glaucoma Service, Department of Ophthalmology, University of Campinas, Campinas, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Cremasco
authors.forename: Graziela
authors.initials: G
authors.lastname: Massa
authors.forename: Vanessa
authors.initials: V
authors.lastname: Gonçalves Vidotti
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Pedroso de Carvalho Lupinacci
authors.forename: Vital Paulino
authors.initials: VP
authors.lastname: Costa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D015588:Observer Variation; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D055815:Young Adult