Sodium chloride – the most common type of salt – is in all your body’s fluids: blood, sweat, and (yep) tears. Your tears contain a little less than one percent salt.
Tears contain greater quantities of water along with other organic and inorganic chemical components like mucin, lipids, lysozyme, lactoferrin, lipocalin, lacritin, sodium and potassium. The salinity of tears is attributed to the presence of salts of sodium and potassium.
This salinity of tears along with the presence of enzymes like lysozyme is responsible for their antimicrobial activity. Basal tears have a salt content similar to blood plasma. The salinity of basal tears disturbs the osmotic balance of bacteria and keeps the cornea in a healthy microbial-free environment. The mineral content of tears also nourishes the tissues associated with eyes. Saline nature of tears also indicates our evolutionary descent from marine organisms.
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