The Amazing Tears.
The tears we cry in joy or sorrow are more than just moisture. For healthy eyes and clear vision the tears must be produced, sit smoothly, drain freely…. and then do it all again continually over the course of the day.
Our tears are complex: only 3- to 4-micron-thick with more than 18 mucins, 491 proteins and at least 153 types of oils. They are a unique fluid that have a number of special functions:
They maintain the hydration of the surface of the eye
They lubricate the eye surface
They nourish the cornea and conjunctiva
They cleanse the eye surface
They defend against bacterial invasion
They buffer the pH of the eye surface
They ensure clear vision
Mucin.
Mucin is a mucus-like gel produced by goblet cells in the conjunctiva. It helps the tears adhere to the eye keeping it moist & lubricated.
Aqueous.
The watery layer is produced by the lacrimal glands to nourish and protect the surface of the eye & washes away debris
Lipid.
The lipid layer is an oily layer produced by the meibomian glands in the eyelids to lubricate and prevent evaporation.