Meibum with increased viscosity, that is thick or pasty and does not flow easily, will not secrete properly, leading to – and exacerbating – evaporative dry eye.
Some experts believe that increased viscosity alone, or with hyperkertinization of the duct epithelium, leads to obstructive meibomian gland dysfunction (MGD). At the same time, this obstruction causes stagnation of the meibum and increased pressure inside the gland. The ducts become dilated and atrophied. Stagnant meibum can also increase bacteria that produce oil-degrading enzymes leading to saponification and the release of toxic mediators. The condition exacerbates meibum viscosity, contributing to the vicious cycle of Dry Eye.
References
Meibomian glands : part IV. Functional interactions in the pathogenesis of meibomian gland dysfunction (MGD)
Knop E, Knop N.
Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft
2009 Nov;106(11):980-7. doi: 10.1007/s00347-009-2044-8.
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