Numerous studies have been done on the tear physiology and stability of the precorneal tear film and various hypotheses explaining the mechanism of tear rupture and formation have been proposed. One hypothesis proposed that the film stability was caused by the spreading of mucin along the lipid‐aqueous interface which increases the film pressure. As the lipid starts diffusing into the mucus‐tear interface, and once the hydrophilicity of the mucus is overwhelmed, the tear film will rupture over the hydrophobic spots. Another hypothesis however, attributes the rupture of the mucous layer, due to van der Waals forces between the epithelium and the mucin, as the cause of tear instability. However, the actual composition of the interfaces between each layer of the precorneal tear film remains unclear and the exact mechanism of the tear film rupture is difficult to pinpoint. This review surveys the literature and summarises current opinions in this fi
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