title: Reproducibility of nerve fiber layer thickness measurements by use of optical coherence tomography.
abstract: OBJECTIVE
  To evaluate the reproducibility of optical coherence tomograph (OCT) retinal nerve fiber layer (RNFL) measurements in normal and glaucomatous eyes by means of the commercially available OCT 2000 instrument (Humphrey Systems, Dublin, CA).
  
  
  METHODS
  Prospective instrument validation study.
  
  
  METHODS
  One eye each from 10 normal subjects and 10 glaucoma patients.
  
  
  METHODS
  Twenty subjects underwent a total of eight scanning sessions during two independent visits. In each session, five circular scans centered on the optic nerve head were performed. The first two sessions were performed by two experienced technicians. Followed by a 30-minute break, a third and a fourth session was completed by the same technicians. This sequence was duplicated on a second visit. Intrasession, intersession, intervisit, and interoperator reproducibility of quadrant and global RNFL measurements were calculated by use of a components of variance model.
  
  
  METHODS
  RNFL thickness.
  
  
  RESULTS
  The coefficient of variation for the mean RNFL thickness was significantly smaller (P = 0.02) in normal eyes (6.9%) than in glaucoma eyes (11.8%). The estimated root mean squared error based on the statistical model using three scans per patient was 5.8 and 8.0 micrometer for normal and glaucoma eyes, respectively. A components of variance model showed most of the variance (79%) to be due to differences between patients. Only a modest contribution to variability was found for session (1%), visit (5%), and operator (2%).
  
  
  CONCLUSIONS
  With the commercially available OCT, our results indicate that the RNFL measurements are reproducible for both normal and glaucomatous eyes.
authors.affiliation: Glaucoma Center and Diagnostic Imaging Laboratory, Department of Ophthalmology, University of California, San Diego, USA.
authors.forename: E Z
authors.initials: EZ
authors.lastname: Blumenthal
authors.forename: J M
authors.initials: JM
authors.lastname: Williams
authors.forename: R N
authors.initials: RN
authors.lastname: Weinreb
authors.forename: C A
authors.initials: CA
authors.lastname: Girkin
authors.forename: C C
authors.initials: CC
authors.lastname: Berry
authors.forename: L M
authors.initials: LM
authors.lastname: Zangwill
mesh_terms: D000328:Adult; D000368:Aged; D003941:Diagnostic Techniques, Ophthalmological; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007368:Interferometry; D009412:Nerve Fibers / Q000473:pathology*; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D013016:Sound; D014054:Tomography / Q000379:methods