title: The diurnal secretory characteristics of individual meibomian glands.
abstract: OBJECTIVE
  To investigate the diurnal secretory characteristics of individual meibomian glands (MGs).
  
  
  METHODS
  Ten subjects (4 females and 6 males) with healthy eyelid appearance and without dry eye symptoms were recruited (mean age = 23.8 +/- 1.8 years). Both right and left lower eyelids were marked in 3 places to locate 5 consecutive MGs in each third (temporal, central, and nasal) of the lower eyelid. A total of 15 MGs per eye were diagnostically expressed for 10 seconds on both right and left lower eyelids every 3 hours for 4 consecutive measurements over a 9-hour period.
  
  
  RESULTS
  Thirty-four percent of all tested MGs yielded liquid secretion at all measurements. Sixty-nine percent of the tested nasal MGs yielded liquid secretion at all measurements in contrast to 31% of the central MGs and only 22% of the temporal MGs. The mean numbers of MGs secreting liquid oil were significantly higher in the nasal section relative to the central and temporal sections at all measurements (p < 0.001, all measurements).
  
  
  CONCLUSIONS
  (1) A single MG is capable of secreting oil on demand over the course of a working day ( approximately 9 hours); (2) nasal MGs were the most likely to secrete upon demand over the course of day compared with the temporal and to a lesser degree the central MGs; and (3) secretory characteristics of individual MGs examined as a function of their location in the lower eyelid does not change diurnally.
authors.affiliation: Korb Associates, Boston, MA 02215, USA. cblackie@tearscience.com
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Blackie
authors.forename: Donald R
authors.initials: DR
authors.lastname: Korb
mesh_terms: D000328:Adult; D001826:Body Fluids / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology*; D005143:Eyelids / Q000502:physiology; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D008537:Meibomian Glands / Q000378:metabolism*; D055815:Young Adult; D008055:Lipids
chemical_list: D008055:Lipids