title: Age-related differences in the normal human cornea: a laser scanning in vivo confocal microscopy study.
abstract: OBJECTIVE
  To quantify and establish baseline normative data for age-related differences in cellular and innervation density in the normal, healthy, human cornea using laser scanning in vivo confocal microscopy.
  
  
  METHODS
  Cross-sectional study of 85 normal subjects assessed via corneal topography and laser scanning in vivo confocal microscopy.
  
  
  RESULTS
  Mean age was 38+/-16 years (range 18-87 years) and 60% of subjects were female. Anterior keratocyte density declined by 0.9% per year (r = -0.423, p<0.001), posterior keratocyte density declined by 0.3% per year (r = -0.250, p = 0.021) and endothelial cell density declined by 0.5% per year (r = -0.615, p<0.001). Sub-basal nerve fibre density declined by 0.9% per year (r = -0.423, p<0.001). No association was observed between age and basal epithelial cell density, or between age and central corneal thickness, corneal astigmatism or horizontal corneal diameter (p>0.05). No association was observed between subject gender and corneal cell or innervation density.
  
  
  CONCLUSIONS
  Using laser scanning in vivo confocal microscopy this study highlights a significant, and relatively linear, reduction in keratocyte and endothelial cell density with increasing subject age. Interestingly, corneal sub-basal nerve fibre density also significantly decreases with increasing age. In vivo laser scanning confocal microscopy provides a safe, non-invasive method for the establishment of normative data and assessment of alterations in human corneal microstructure following surgery or disease processes.
authors: Department of Ophthalmology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand
authors: R L
authors: RL
authors: Niederer
authors: D
authors: D
authors: Perumal
authors: T
authors: T
authors: Sherwin
authors: C N J
authors: CN
authors: McGhee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D002452:Cell Count; D003315:Cornea / Q000166:cytology* / Q000294:innervation; D019781:Corneal Topography / Q000379:methods; D004728:Endothelium, Corneal / Q000166:cytology; D019573:Epithelium, Corneal / Q000166:cytology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D047569:Laser Scanning Cytometry / Q000379:methods; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009412:Nerve Fibers / Q000648:ultrastructure