At each blink, the eyelids deposit a tear film on the entire ocular surface. This film keeps the eye hydrated and clean, making the dust and impurities flow out, preventing them from damaging the cornea. In addition, tears contain antibacterial substances that remove the risk of infections.
The tears are formed by 3 components: a prominent aqueous (liquid) part hydrates the eye; a sort of viscous mucus causes the tear film to adhere and protects the cornea; a lipid (oily) portion prevents the tear film from evaporating.
Basal tears are composed mainly of water, but also contain electrolytes (Na +, K + and Cl-), glucose, proteins (albumins, lactoferrin, immunoglobulins etc.), free amino acids, urea, exfoliated cells and lysozyme (enzyme with antibacterial action) .
