title: Repeatability of optic nerve head parameters measured by spectral-domain OCT in healthy eyes.
abstract: OBJECTIVE
  To evaluate the repeatability of optic nerve head (ONH) measurements by spectral-domain optical coherence tomography.
  
  
  METHODS
  Three scans were acquired in 32 healthy subjects during one session. Using Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA), the cup-to-disc ratio (CDR), disc area, rim area, cup volume, and horizontal and vertical CDRs were investigated. Repeatability was assessed by the coefficient of variation (COV), the test-retest intrasession variability, and the intraclass correlation coefficient (ICC).
  
  
  RESULTS
  Good repeatability was achieved for all parameters, with a COV of 4.23% or less and ICCs of 0.98 or greater for all measurements. Test-retest intrasession variability was 0.024 for CDR, 0.121 mm(2) for disc area, 0.087 mm(2) for rim area, 0.017 mm(3) for cup volume, and 0.048 for horizontal and vertical CDR.
  
  
  CONCLUSIONS
  In healthy eyes, Cirrus HD-OCT provides repeatable measurements of ONH parameters.
authors.affiliation: G.B. Bietti Eye Foundation-IRCCS, Rome, Italy. giacomo.savini@alice.it
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
authors.forename: Michele
authors.initials: M
authors.lastname: Carbonelli
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Parisi
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
mesh_terms: D006801:Humans; D008875:Middle Aged; D009898:Optic Disk / Q000033:anatomy & histology*; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000295:instrumentation*