title: Reproducibility of peripapillary retinal nerve fiber layer thickness and optic nerve head parameters measured with cirrus HD-OCT in glaucomatous eyes.
abstract: OBJECTIVE
  To assess the reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters measured with Cirrus HD-OCT in glaucomatous eyes.
  
  
  METHODS
  Fifty-five glaucomatous eyes were included in the study. The optic disc cube 200 × 200 protocol was used to obtain three scans during the same visit to evaluate the intravisit reproducibility. One scan on 4 additional days within a 2-month period of the first session was obtained to assess intervisit reproducibility. Intraclass correlation coefficient (ICC), coefficient of variation (CV), and test-retest SD (TRT SD) were calculated for each RNFL and ONH parameter. The formula 1.645 × √2 × intervisit TRT SD provides an upper tolerance limit to variability beyond which nonphysiologic change should be considered.
  
  
  RESULTS
  All ICCs were excellent, ranging from 83.9% to 99.2% for intravisit measurements and from 80.8% to 99.1% for intervisit measurements. Cup/disc area ratio had the lowest CV (1.1%) in either type of measurement, followed by average RNFL thickness (1.9% and 2.7%). Nasal clock hours and quadrants showed the poorest reproducibility as did the clock hour directly temporally. The intervisit tolerance limit for average RNFL thickness was 3.89 μm.
  
  
  CONCLUSIONS
  Intravisit and intervisit measurements of peripapillary RNFL thickness and ONH parameters with Cirrus HD-OCT showed excellent reproducibility, indicating that this instrument may be useful in monitoring glaucoma progression. When comparing two measurements from the same eye on two different visits, a reproducible decrease in average RNFL thickness of approximately 4 μm or more may be considered a statistically significant change from baseline.
authors.affiliation: Bascom Palmer Eye Institute, Miller School of Medicine, University of Miami, Miami, Florida 33136, USA.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mwanza
authors.forename: Robert T
authors.initials: RT
authors.lastname: Chang
authors.forename: Donald L
authors.initials: DL
authors.lastname: Budenz
authors.forename: Mary K
authors.initials: MK
authors.lastname: Durbin
authors.forename: Mohamed G
authors.initials: MG
authors.lastname: Gendy
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: William J
authors.initials: WJ
authors.lastname: Feuer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence