title: Reliability of nerve fiber layer thickness measurements using optical coherence tomography in normal and glaucomatous eyes.
abstract: OBJECTIVE
  To evaluate the reliability of nerve fiber layer (NFL) thickness measurements by optical coherence tomography (OCT) in normal and glaucomatous eyes.
  
  
  METHODS
  Prospective, comparative, observational case series and instrument validation study.
  
  
  METHODS
  Twenty-four glaucomatous patients were compared with 24 gender- and age-matched normal subjects.
  
  
  METHODS
  Each individual underwent OCT measurements of NFL thickness. Five repetitions of a series of scans on five separate occasions within a 0.5-month period were performed. Each eye was scanned at three different nerve head programs (1.5 radius [R], R = 1.73 mm, 2.0 R). For each option (1.5 R, R = 1.73 mm, and 2.0R) and region (superior, inferior, temporal, nasal, and overall mean), variance components and intraclass correlation coefficients were determined using repeated measures regression. In these models, NFL thickness, as measured by OCT, was assumed to have three variance components: intersubject, intervisit (within-subject between-dates), and intravisit (within-subject within-date). The intraclass correlation coefficient (intersubject variance/total variance) was used as a measure of reliability.
  
  
  METHODS
  Measurements of NFL thickness using OCT were performed.
  
  
  RESULTS
  Reliability values, as measured by intraclass correlation coefficients, resulted as follows: 1.5 R, 0.54/0.52 (normal/glaucoma); R = 1.73 mm, 0.50/0.50; 2.0 R, 0.49/0.50.
  
  
  CONCLUSIONS
  Our results indicate that the recent commercially available OCT provides reliable NFL thickness measurements in both healthy and glaucomatous eyes with each circle radius tested. The greatest amount of variability can be attributed to intersubject differences.
authors.affiliation: Department of Medicine and Aging Sciences, Section of Ophthalmology, University G. D'Annunzio, Chieti, Italy. paolocarpineto@hotmail.com
authors.forename: Paolo
authors.initials: P
authors.lastname: Carpineto
authors.forename: Marco
authors.initials: M
authors.lastname: Ciancaglini
authors.forename: Eduardo
authors.initials: E
authors.lastname: Zuppardi
authors.forename: Gennaro
authors.initials: G
authors.lastname: Falconio
authors.forename: Emanuele
authors.initials: E
authors.lastname: Doronzo
authors.forename: Leonardo
authors.initials: L
authors.lastname: Mastropasqua
mesh_terms: D000328:Adult; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007368:Interferometry; D008027:Light; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D014054:Tomography / Q000379:methods