title: Epidemiology of the optic nerve grey crescent in the Reykjavik Eye Study.
abstract: OBJECTIVE
  To establish the epidemiology of the grey crescent in a white population within the age range most susceptible to glaucoma.
  
  
  METHODS
  Bruce Shields was first to use this term to describe a localised, physiological pigmentation of the optic nerve neuroretinal rim tissue that is distinct from peripapillary pigmentation. An experienced glaucomatologist (KFD) evaluated stereofundus photographs of the participants of the Reykjavik Eye Study (RES)-a random sample from the national population census including people 50 years and older. 1012 right eyes could be evaluated for grey crescent.
  
  
  RESULTS
  The prevalence of grey crescent in the right eyes was 22.0% (95% CI 10 to 25). It was more commonly found in women (27.0%: 95% CI 23 to 30) than in men (17.0%: 95% CI 14 to 21), and was most often located temporally (36.9%), 360 degrees (15.9%), or nasally (15.4%). The spherical equivalent was +1.30 dioptres (D) for those with and +0.80 D for those without grey crescent (p = 0.002), respectively. Vertical optic disc diameters were 0.203 v 0.195 units (p<0.001). There was no difference in the prevalence of grey crescent in glaucomatous or non-glaucomatous eyes (OR = 1.05, 95% CI 0.49 to 2.26). The prevalence of a grey crescent was inversely related to the prevalence of peripapillary atrophy (p = 0.001).
  
  
  CONCLUSIONS
  The grey crescent needs to be recognised as a physiological variant in order to avoid falsely labelling eyes as having glaucomatous optic nerve damage.
authors.affiliation: University of Ottawa Eye Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6.
authors.forename: O
authors.initials: O
authors.lastname: Jonsson
authors.forename: K F
authors.initials: KF
authors.lastname: Damji
authors.forename: F
authors.initials: F
authors.lastname: Jonasson
authors.forename: A
authors.initials: A
authors.lastname: Arnarsson
authors.forename: T
authors.initials: T
authors.lastname: Eysteinsson
authors.forename: H
authors.initials: H
authors.lastname: Sasaki
authors.forename: K
authors.initials: K
authors.lastname: Sasaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001284:Atrophy / Q000453:epidemiology; D005260:Female; D005451:Fluorescein Angiography; D005901:Glaucoma / Q000453:epidemiology* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000453:epidemiology* / Q000473:pathology / Q000503:physiopathology; D010859:Pigmentation Disorders / Q000453:epidemiology* / Q000473:pathology / Q000503:physiopathology; D015995:Prevalence; D017678:Sex Distribution