title: Corneal fluorescence in relation to genetic and environmental factors: a twin study.
abstract: OBJECTIVE
  Corneal fluorescence is believed to be caused by advanced glycation end products formed by non-enzymatic glycation on corneal proteins. The purpose of the present twin study was to examine whether the process is related to genetic or environmental factors.
  
  
  METHODS
  Corneal fluorescence was measured in 59 monozygotic and 54 dizygotic twin pairs. The influences of genetic and environmental factors were estimated using structural equation modelling.
  
  
  RESULTS
  Interindividual variation in corneal fluorescence was attributable to environmental factors, whereas the effect of genetic factors was of little or no significance. Corneal fluorescence correlated significantly with smoking habits (r = 0.38) and the 2-hour oral glucose tolerance test response (r = 0.27), and increased with age (p < 0.0001).
  
  
  CONCLUSIONS
  Fluorophore accumulation in the cornea was attributable to age and environmental effects, of which smoking was the most conspicuous identifiable factor, although glucose was also of relevance. However, the greater part of interindividual variation in corneal fluorescence remains unexplained.
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D003315:Cornea / Q000502:physiology*; D004777:Environment; D005260:Female; D005453:Fluorescence; D005951:Glucose Tolerance Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D012907:Smoking; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic