title: Test-retest variability of retinal nerve fiber layer thickness and macular ganglion cell-inner plexiform layer thickness measurements using spectral-domain optical coherence tomography.
abstract: OBJECTIVE
  To evaluate the test-retest variability of spectral-domain optical coherence tomography (OCT) in measurement of retinal nerve fiber layer (RNFL) thickness and macular ganglion cell-inner plexiform layer (GCIPL) thickness.
  
  
  METHODS
  A total of 65 eyes of healthy subjects were enrolled in this observational cross-sectional study. RNFL thickness and GCIPL thickness were measured using the repeat scan optic cube and macular cube protocol using Cirrus HD-OCT (software version 6.0). A single operator obtained 3 measurements during 1 session to determine test-retest variability. Intrasession repeatability was defined by intraclass correlation, limits of agreement, and coefficient of variation.
  
  
  RESULTS
  The mean age of patients was 37.89±15.11 years (range, 10 to 70 y). The mean RNFL thickness readings as measured during 3 sessions were 93.89±9.73, 93.63±10.00, and 93.55±9.64 μm and average GCIPL thickness measurements were 82.90±4.61, 82.98±4.24, and 83.06±4.36 μm, respectively. Coefficient of variation was 1.2 for average RNFL thickness and 0.82 for average GCIPL thickness. The intraclass correlation coefficient showed a good correlation between repeat measurements for both average RNFL and GCC thicknesses (0.994 and 0.990, respectively). The limits of agreement (95% confidence interval) for the 3 sessions ranged from -3.61 to 4.13 μm for the average RNFL thickness and -2.55 to 2.40 μm for GCIPL thickness measurements.
  
  
  CONCLUSIONS
  In healthy eyes, Cirrus HD-OCT shows excellent intrasession repeatability for RNFL and GCIPL thickness measurements.
authors.affiliation: *Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India †Ivey Eye Institute, Schulich School of Medicine and Dentistry, London, ON, Canada.
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Wadhwani
authors.forename: Shveta J
authors.initials: SJ
authors.lastname: Bali
authors.forename: Raji
authors.initials: R
authors.lastname: Satyapal
authors.forename: Dewang
authors.initials: D
authors.lastname: Angmo
authors.forename: Reetika
authors.initials: R
authors.lastname: Sharma
authors.forename: Veena
authors.initials: V
authors.lastname: Pandey
authors.forename: Tanuj
authors.initials: T
authors.lastname: Dada
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers; D009898:Optic Disk / Q000033:anatomy & histology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000166:cytology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D014065:Tonometry, Ocular; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology