title: The normal optic nerve head.
abstract: BACKGROUND
  The normal optic nerve head varies from one person to another, and there is often intraindividual variation as well. Factors such as race and age play an important role in distinguishing what may be considered normal variations in optic nerve head appearance.
  
  
  METHODS
  A literature search and review of the latest studies on the optic nerve head was conducted.
  
  
  RESULTS
  Results of recent studies showed that variations in the average cup-to-disc ratio exist for different races, and with age there is a gradual loss of nerve fibers leading to an overall increase in the cup-to-disc ratio. There is also evidence that congenitally larger optic nerves have larger cup-to-disc ratios and more nerve fibers. Smaller optic nerves, in contrast, have smaller cup-to-disc ratios and fewer nerve fibers. These findings are presented along with sample photographs depicting the normal variations in optic nerve head appearance.
  
  
  CONCLUSIONS
  Over the past 30 years, technology has allowed for changing views about what may be considered normal in reference to the optic nerve head. This information is valuable to the eye care practitioner in helping to make appropriate patient care management decisions.
authors.affiliation: VA Greater Los Angeles Healthcare System, Sepulveda Ambulatory Care Center & Nursing Home, California, USA. ntamsing@hotmail.com
authors.forename: N M
authors.initials: NM
authors.lastname: Sing
authors.forename: S F
authors.initials: SF
authors.lastname: Anderson
authors.forename: J C
authors.initials: JC
authors.lastname: Townsend
mesh_terms: D000375:Aging / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009412:Nerve Fibers / Q000502:physiology; D009898:Optic Disk / Q000033:anatomy & histology* / Q000502:physiology; D044469:Racial Groups; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000502:physiology; D012727:Sex Characteristics