Meibum Does not Flow to Tear Film

In some patients, meibum may be produced but, because of blockage, it does not flow out of the meibomian glands and onto the tear film, resulting in evaporative dry eye.

Blockage may be due to stagnant meibum, thick or hardened meibum, fibrotic tissue, atrophy or drop out anywhere along the length of the gland, infections, inflammation, or closed glands, all signs of meibomian gland dysfunction (MGD).

Reference

The International Workshop on Meibomian Gland Dysfunction: report of the Subcommittee on Anatomy, Physiology, and Pathophysiology of the meibomian gland
Knop E, Knop N, Millar T, Obata H, Sullivan DA.
Investigative Ophthalmology and Visual Science
2011 Mar 30;52(4):1938-78. doi: 10.1167/iovs.10-6997c. Print 2011 Mar. PMID:21450915
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