Like some other fats, meibum becomes hard when it becomes cold. When meibum hardens it does not flow and is not secreted during blinking, leading to evaporative dry eye.
Meibomian lipid films and the impact of temperature
Butovich IA, Arciniega JC, Wojtowicz JC
Investigative Ophthalmology & Visual Science
2010 Nov;51(11):5508-18. doi: 10.1167/iovs.10-5419. Epub 2010 Jul 7.
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