The Dry Eye Zone

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Abstract: How long it takes for a healthy MG to refill its tank

Cornea. 2009 Apr;28(3):293-7.
Recovery time of an optimally secreting meibomian gland.

Blackie CA, Korb DR.
Korb Associates, Boston, MA, USA.

PURPOSE: To investigate the times for an optimally secreting meibomian gland (OSMG) to be drained of available liquid secretion, to recover with expressible liquid secretion, and then to be redrained.

METHODS: Twelve subjects with no dry eye symptoms and mean age 21.3 +/- 1.9 years were recruited. Lipid layer thickness and tear breakup time were measured. The number of meibomian glands yielding liquid secretion for both right and left lower eyelids was counted using a meibomian gland diagnostic expression device. A single OSMG in the central third of the right and left lower eyelids was marked. A second diagnostic expression device was used to drain the liquid secretion from each marked gland. The times to drain the gland of available liquid secretion, for the drained gland to recover, and then be redrained were measured.

RESULTS: The mean lipid layer thickness and tear breakup time were 98 +/- 44 nm and 12.4 +/- 1.9 seconds. The mean time to drain the marked meibomian gland was 12.1 +/- 3.5 seconds, range: 8-20 seconds; for partial recovery of the drained meibomian gland was 2.17 +/- 0.49 hours, range: 1.5-2.5 hours; and to redrain the meibomian gland after recovery was 5.54 +/- 1.9 seconds, range: 5-10 seconds.

CONCLUSIONS: This report shows that (1) a single OSMG can be drained of its liquid secretion in 8-20 seconds upon application of a constant force of 1 g/mm, and (2) a partial recovery occurs after approximately 2 hours, evidenced by detectable liquid secretion which then expressed for only half of the original time.