title: Laser scanning tomography of optic discs of the normal Japanese population in a population-based setting.
abstract: OBJECTIVE
  To evaluate the optic disc characteristics using the Heidelberg retina tomograph (HRT) II in a large sample of normal Japanese subjects.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  A total of 3576 eyes of 2036 normal subjects, with good-quality HRT II images, of 6042 eyes of 3021 subjects aged 40 years or more who participated in the Tajimi Study, a population-based eye study in Japan.
  
  
  METHODS
  Optic disc parameters were obtained using HRT II, and the association of gender, age, height, weight, blood pressure, ocular perfusion pressure, refraction, intraocular pressure (IOP), central corneal thickness (CCT), and disc size on HRT parameters was assessed using simple and multiple regression analyses.
  
  
  METHODS
  HRT parameters, including disc area, cup area, rim area, cup-to-disc area ratio, cup volume, rim volume, mean cup depth, maximum cup depth, height variation contour, cup shape measure, mean retinal nerve fiber layer (RNFL) thickness, and RNFL cross-sectional area, and the crude and partial correlations of the potential confounders with the HRT parameters.
  
  
  RESULTS
  Disc area, cup-to-disc area ratio, and rim area averaged 2.06+/-0.41 mm(2) (mean+/-standard deviation), 0.23+/-0.13, and 1.55+/-0.29 mm(2), respectively. All HRT parameters were strongly or moderately correlated between right and left eyes (Pearson's correlation coefficients = 0.45-0.83, P<0.001). Absolute inter-eye differences in several HRT parameters were positively correlated with disc area (P<0.05). Multiple regression analyses adjusting for the confounders showed weak but significant correlations of height, refractive error, IOP, and CCT with several HRT parameters (partial correlation coefficient (absolute value) = 0.04-0.16, P<0.05), and moderate or weak but significant correlations of disc area with all HRT parameters (partial correlation coefficient [absolute value] = 0.05-0.73, P<0.05). Gender, weight, blood pressure, and ocular perfusion pressure did not significantly correlate with HRT parameters.
  
  
  CONCLUSIONS
  This report presents reference data of normality for the HRT parameters based on a large sample of normal Japanese subjects. There were small but significant influences of height, refractive error, IOP, and CCT on several HRT parameters. Many HRT parameters were moderately or weakly affected by disc size.
  
  
  BACKGROUND
  Proprietary or commercial disclosure may be found after the references.
authors.affiliation: Division of Ophthalmology and Visual Sciences, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Abe
authors.forename: Motohiro
authors.initials: M
authors.lastname: Shirakashi
authors.forename: Tae
authors.initials: T
authors.lastname: Tsutsumi
authors.forename: Makoto
authors.initials: M
authors.lastname: Araie
authors.forename: Atsuo
authors.initials: A
authors.lastname: Tomidokoro
authors.forename: Aiko
authors.initials: A
authors.lastname: Iwase
authors.forename: Goji
authors.initials: G
authors.lastname: Tomita
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D044466:Asian People / Q000208:ethnology; D001369:Axons; D001794:Blood Pressure / Q000502:physiology; D001824:Body Constitution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000033:anatomy & histology*; D012016:Reference Values; D012165:Retinal Ganglion Cells / Q000166:cytology; D012737:Sex Factors; D014054:Tomography; D014065:Tonometry, Ocular