title: The effects of age, gender, and fluid dynamics on the concentration of tear film epidermal growth factor.
abstract: OBJECTIVE
  To identify the relationship between epidermal growth factor (EGF) concentration in human tears and clinical tear-flow parameters and how these vary with age and gender.
  
  
  METHODS
  Tear samples were collected with minimal stimulation from 68 healthy and asymptomatic adults (33 men, 35 women), aged 21-88 years. EGF concentrations were determined by sandwich enzyme-linked immunosorbent assay (ELISA) in 65 cases. Schirmer tests were performed without anesthesia, and the clearance of fluorescein from the tear film assessed. The Tear Function Index (TFI) was calculated from these values.
  
  
  RESULTS
  There were approximately equal numbers of male and female subjects with a similar age distribution for each gender (48 +/- 3 and 51 +/- 3 years, mean +/- SEM, respectively). Ninety percent of tear EGF concentrations were between 0.75 and 7.1 ng/ml. Tear EGF level correlated significantly with Schirmer I value, but not with age. Schirmer I value correlated with tear clearance [LN(TCR)] but not with age. Tear EGF concentrations were significantly higher for men (3.4 +/- 0.3 ng/ml) than for women (2.4 +/- 0.3 ng/ml; p = 0.043).
  
  
  CONCLUSIONS
  EGF concentrations is tear samples from normal humans were found to correlate with gender and Schirmer I value but not with tear clearance.
authors.affiliation: Ocular Surface and Tear Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, FL 33136, USA.
authors.forename: A
authors.initials: A
authors.lastname: Nava
authors.forename: K
authors.initials: K
authors.lastname: Barton
authors.forename: D C
authors.initials: DC
authors.lastname: Monroy
authors.forename: S C
authors.initials: SC
authors.lastname: Pflugfelder
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D004815:Epidermal Growth Factor / Q000378:metabolism*; D005260:Female; D019793:Fluorescein; D005452:Fluoresceins; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011897:Random Allocation; D012723:Sex; D013666:Tears / Q000502:physiology*
chemical_list: D005452:Fluoresceins; D004815:Epidermal Growth Factor; D019793:Fluorescein