title: Retinal nerve fibre layer thickness profile in normal eyes using third-generation optical coherence tomography.
abstract: OBJECTIVE
  To establish four normal retinal nerve fibre layer (RNFL) thickness radial profiles based on third-generation optical coherence tomography (OCT) and to compare them with previously reported histologic measurements.
  
  
  METHODS
  A total of 20 normal eyes were studied. A circular scan was adjusted to the size of the optic disc and three scans were performed with this radius and every 200 microm thereafter, up to a distance of 1400 microm. Four different radial sections (superotemporal, superonasal, inferonasal, and inferotemporal) were studied to establish RNFL thickness OCT profiles. Additionally, two radial scans orientated at 45 and 135 degrees crossing the optic disc centre were performed in six of 20 eyes, and RNFL thickness was measured at disc margin.
  
  
  RESULTS
  Quadrant location and distance from disc margin interaction in RNFL thickness was statistically significant (P<0.001). The RNFL thickness decreased (P<0.001) as the distance from the disc margin increased for all sections. The measurements automatically generated by the OCT built-in software were thinner (P<0.001) than histologic ones close to the disc margin.
  
  
  CONCLUSIONS
  Four normal OCT RNFL profiles were established and compared with histological data obtained from the same area. RNFL measurements assessed by OCT 3 were significantly thinner close to the optic disc margin.
authors.affiliation: Glaucoma Section, Hospital de Olhos de Araraquara, Araraquara-SP, Brazil. miski@uol.com.br
authors.forename: M
authors.initials: M
authors.lastname: Skaf
authors.forename: A B
authors.initials: AB
authors.lastname: Bernardes
authors.forename: J A
authors.initials: JA
authors.lastname: Cardillo
authors.forename: R A
authors.initials: RA
authors.lastname: Costa
authors.forename: L A S
authors.initials: LA
authors.lastname: Melo
authors.forename: J C
authors.initials: JC
authors.lastname: Castro
authors.forename: R
authors.initials: R
authors.lastname: Varma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000648:ultrastructure*; D009898:Optic Disk / Q000033:anatomy & histology; D012165:Retinal Ganglion Cells / Q000166:cytology*; D041623:Tomography, Optical Coherence / Q000379:methods