title: Correlation between retinal nerve fibre layer thickness and optic nerve head size: an optical coherence tomography study.
abstract: OBJECTIVE
  To investigate the correlation between retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) size in normal white subjects by means of optical coherence tomography (OCT).
  
  
  METHODS
  54 eyes of 54 healthy subjects aged between 15 and 54 underwent peripapillary RNFL thickness measurement by a series of three circular scans with a 3.4 mm diameter (Stratus OCT, RNFL Thickness 3.4 acquisition protocol). ONH analysis was performed by means of six radial scans centred on the optic disc (Stratus OCT, Fast Optic Disc acquisition protocol). The mean RNFL values were correlated with the data obtained by ONH analysis.
  
  
  RESULTS
  The superior, nasal, and inferior quadrant RNFL thickness showed a significant correlation with the optic disc area (R = 0.3822, p = 0.0043), (R = 0.3024, p = 0.026), (R = 0.4048, p = 0.0024) and the horizontal disc diameter (R = 0.2971, p = 0.0291), (R = 0.2752, p = 0.044), (R = 0.3970, p = 0.003). The superior and inferior quadrant RNFL thickness was also positively correlated with the vertical disc diameter (R = 0.3774, p = 0.0049), (R = 0.2793, p = 0.0408). A significant correlation was observed between the 360 degrees average RNFL thickness and the optic disc area and the vertical and horizontal disc diameters of the ONH (R = 0.4985, p = 0.0001), (R = 0.4454, p = 0.0007), (R = 0.4301, p = 0.0012).
  
  
  CONCLUSIONS
  RNFL thickness measurements obtained by Stratus OCT increased significantly with an increase in optic disc size. It is not clear if eyes with large ONHs show a thicker RNFL as a result of an increased amount of nerve fibres or to the shorter distance between the circular scan and the optic disc edge.
authors.affiliation: Centro Salus, via Saffi 4H, 40131 Bologna, Italy. giacomo.savini@fastwebnet.it
authors.forename: G
authors.initials: G
authors.lastname: Savini
authors.forename: M
authors.initials: M
authors.lastname: Zanini
authors.forename: V
authors.initials: V
authors.lastname: Carelli
authors.forename: A A
authors.initials: AA
authors.lastname: Sadun
authors.forename: F N
authors.initials: FN
authors.lastname: Ross-Cisneros
authors.forename: P
authors.initials: P
authors.lastname: Barboni
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000648:ultrastructure*; D009898:Optic Disk / Q000033:anatomy & histology*; D012016:Reference Values; D012165:Retinal Ganglion Cells / Q000166:cytology*; D041623:Tomography, Optical Coherence / Q000379:methods