Abstract
Purpose: :
To investigate the diurnal secretory characteristics of individual meibomian glands.
Methods: :
10 subjects (4 females, 6 males) with healthy eyelid appearance, without dry eye symptoms, and taking no topical or systemic medications known to affect eye dryness, were recruited (mean age = 23.8 ± 1.8 yrs). Both right and left lower lids were marked in three places to locate the first of five consecutive meibomian glands in each marked third (temporal, central and nasal) of the lower lid. Each of the three sections, for a total of 15 meibomian glands per eye, was diagnostically expressed for 10 seconds using a previously reported standardized diagnostic expression device. The presence or absence of secretion as well as the secretion quality of each meibomian gland was recorded. This procedure was performed on both right and left lower lids every 3 hours for 4 consecutive measurements over a nine-hour period.
Results: :
In healthy young eyes, 34% of all tested MGs yielded liquid secretion at all four measurements. 69% of the tested nasal MGs yielded liquid secretion at all four measurements in contrast to 31% of the central MGs and only 22% of the temporal MGs. The mean numbers of MGs secreting liquid oil for each test section were significantly higher in the nasal section relative to the central and temporal sections: nasal = 4.6 ± 0.18, Central = 3.4 ± 0.43, temporal = 3.1 ± 0.45 (p = 0.004).
Conclusions: :
This report shows 1) a single meibomian gland is capable of secreting oil continually over the course of a working day (~ 9 hours), 2) The nasal meibomian glands were the most likely to secrete continually over the course of day compared to the temporal and to a lesser degree the central meibomian glands, 3) the nasal MGs show lower variability in the likelihood of secretion relative to the central and temporal MGs.
Keywords: eyelid • cornea: tears/tear film/dry eye • lipids