title: Effect of optic disc size or age on evaluation of optic disc variables.
abstract: OBJECTIVE
  It has been reported that the number of optic nerve fibres decrease with age, and the cup/disc (C/D) ratio increases as the optic disc size increases. Consequently, the normal value of the optic disc variables measured by an optic disc analyser may change according to the optic disc size or age. The effect of individual variations in optic disc size or age on interpretation of optic disc variables was investigated.
  
  
  METHODS
  Topographic optic disc variables of 104 normal Asian adults of both sexes aged 40 to 68 were measured using a confocal scanning laser ophthalmoscope (TopSS, Laser Diagnostic Technologies, Inc). Fourteen variables were evaluated according to the optic disc size or age. Statistical analysis was done by regression analysis.
  
  
  RESULTS
  With an increase in optic disc size, the increase in cup shape, effective area, 1/2 depth area, C/D ratio, neuroretinal rim area, volume above, volume below, and 1/2 depth volume were statistically significant (p < 0.05). However, contour variation, mean contour depth, average depth, maximum depth, average slope, and maximum slope were not affected (p > 0.1). Age did not have any significant influence on optic disc variables (p > 0.1).
  
  
  CONCLUSIONS
  Optic disc size, but not age, should be considered in the interpretation of optic disc variables.
authors.affiliation: Department of Ophthalmology, Samsung Medical Center, College of Medicine, Sungkyunkwan University, Seoul, Korea.
authors.forename: C
authors.initials: C
authors.lastname: Kee
authors.forename: H
authors.initials: H
authors.lastname: Koo
authors.forename: Y
authors.initials: Y
authors.lastname: Ji
authors.forename: S
authors.initials: S
authors.lastname: Kim
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000033:anatomy & histology*; D012016:Reference Values; D015203:Reproducibility of Results