title: Repeatability of Foveal Measurements Using Spectralis Optical Coherence Tomography Segmentation Software.
abstract: OBJECTIVE
  To investigate repeatability and reproducibility of thickness of eight individual retinal layers at axial and lateral foveal locations, as well as foveal width, measured from Spectralis spectral domain optical coherence tomography (SD-OCT) scans using newly available retinal layer segmentation software.
  
  
  METHODS
  High-resolution SD-OCT scans were acquired for 40 eyes of 40 young healthy volunteers. Two scans were obtained in a single visit for each participant. Using new Spectralis segmentation software, two investigators independently obtained thickness of each of eight individual retinal layers at 0°, 2° and 5° eccentricities nasal and temporal to foveal centre, as well as foveal width measurements. Bland-Altman Coefficient of Repeatability (CoR) was calculated for inter-investigator and inter-scan agreement of all retinal measurements. Spearman's ρ indicated correlation of manually located central retinal thickness (RT0) with automated minimum foveal thickness (MFT) measurements. In addition, we investigated nasal-temporal symmetry of individual retinal layer thickness within the foveal pit.
  
  
  RESULTS
  Inter-scan CoR values ranged from 3.1 μm for axial retinal nerve fibre layer thickness to 15.0 μm for the ganglion cell layer at 5° eccentricity. Mean foveal width was 2550 μm ± 322 μm with a CoR of 13 μm for inter-investigator and 40 μm for inter-scan agreement. Correlation of RT0 and MFT was very good (ρ = 0.97, P < 0.0005). There were no significant differences in thickness of any individual retinal layers at 2° nasal compared to temporal to fovea (P > 0.05); however this symmetry could not be found at 5° eccentricity.
  
  
  CONCLUSIONS
  We demonstrate excellent repeatability and reproducibility of each of eight individual retinal layer thickness measurements within the fovea as well as foveal width using Spectralis SD-OCT segmentation software in a young, healthy cohort. Thickness of all individual retinal layers were symmetrical at 2°, but not at 5° eccentricity away from the fovea.
authors.affiliation: Applied Vision Research Centre, The Henry Wellcome Laboratories for Vision Sciences, City University London, Northampton Square, London, EC1V 0HB, United Kingdom.
authors.forename: Irene
authors.initials: I
authors.lastname: Ctori
authors.affiliation: Applied Vision Research Centre, The Henry Wellcome Laboratories for Vision Sciences, City University London, Northampton Square, London, EC1V 0HB, United Kingdom.
authors.forename: Byki
authors.initials: B
authors.lastname: Huntjens
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005584:Fovea Centralis / Q000166:cytology / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012160:Retina / Q000166:cytology / Q000502:physiology; D012984:Software; D041623:Tomography, Optical Coherence / Q000379:methods* / Q000592:standards; D055815:Young Adult