title: Variation of nerve fibre layer thickness measurements with age and ethnicity by scanning laser polarimetry.
abstract: OBJECTIVE
  Scanning laser polarimetry is a new technique allowing quantitative analysis of the retinal nerve fibre layer in vivo. This technique was employed to investigate the variation of the retinal nerve fibre layer thickness in a group of normal subjects of different ages and ethnic groups.
  
  
  METHODS
  150 normal volunteers of different ages and ethnic groups were recruited for this study. Three consecutive 15-degree polarimetric maps were acquired for each subjects. Nerve fibre layer thickness measurements were obtained at 1.5 disc diameters from the optic nerve. Four 90-degree quadrants were identified.
  
  
  RESULTS
  The mean nerve fibre layer thickness varied from a minimum of 55.4 microns to a maximum of 105.3 microns, with a mean thickness value of 78.2 (SD 10.6) microns. Superior and inferior quadrants showed a comparatively thicker nerve fibre layer than nasal and temporal quadrants. Retinal nerve fibre layer thickness is inversely correlated with age (p < 0.001). White people showed thicker nerve fibre layers than Afro-Caribbeans (p = 0.002).
  
  
  CONCLUSIONS
  The results indicate a progressive reduction of the nerve fibre layer thickness with increasing age. This may be due to a progressive loss of ganglion axons with age as suggested in postmortem studies. A racial difference in nerve fibre layer thickness is present between whites and Afro-Caribbeans.
authors.affiliation: Glaucoma Unit, Moorfields Eye Hospital, London.
authors.forename: D
authors.initials: D
authors.lastname: Poinoosawmy
authors.forename: L
authors.initials: L
authors.lastname: Fontana
authors.forename: J X
authors.initials: JX
authors.lastname: Wu
authors.forename: F W
authors.initials: FW
authors.lastname: Fitzke
authors.forename: R A
authors.initials: RA
authors.lastname: Hitchings
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy / Q000379:methods*; D009900:Optic Nerve / Q000166:cytology*; D044469:Racial Groups; D012044:Regression Analysis; D015203:Reproducibility of Results; D012160:Retina / Q000166:cytology*