What are Tears?
We normally think of tears as the eye moisture when we cry or when our eyes "water". However, a thin film of tears must constantly be produced and washed over our eyes to keep them moist. This eye moisture is referred to as the tear film.
The tear film is the body's natural mechanism for protecting the surface of the eye from the irritating effects of dirt, dust, and other airborne particles, as well as from infection. The tear film helps to create a smooth surface so vision stays clear and undistorted, and eyes stay lubricated and comfortable.
The tear film has three main components: lipid, aqueous, and mucins. Lipids form an oily layer on the outside of the tear film and help slow down evaporation of tears. Without sufficient lipids, our natural tears evaporate too quickly–which may result in dry eye.
The largest portion of the tear film is made of a water-based component called aqueous, with different types and concentrations of mucins (sticky proteins) throughout. The thickest concentration of mucins is at the eye's surface. Since the eye's surface is naturally water repellant, the mucins are needed to create a water attracting surface so the aqueous will spread over the eye.
Each tear film component is needed in balance to create the necessary eye moisture that keeps our eyes comfortable. If any one is missing or damaged, this eye moisture will be depleted and our eyes will feel dry and irritated.
