Tears have 3 layers
Although tears can be underestimated as simple droplets of water, their chemical and physiological makeup are much more complex. As mentioned in a previous slide, all three types of tears contain water, salt, and varying amounts of proteins. Even when we aren’t crying, we still gain benefit from tear production: every time we blink, a protective film of tears covers and lubricates our eyes, preventing dry eye, reducing the risk of eye infections, and clearing out foreign particles. Incredibly, every one of our tears has three layers: an oil (lipid) layer, a water (aqueous) layer, and a mucin layer. The outer oil layer seals the tear film, while the middle aqueous layer lubricates the eye and washes away irritants, and the inner mucin layer allows the tear to spread evenly over the eye while providing nourishment to the cornea. All three are necessary to maintain proper eye health, and if any one is disturbed, it can result in symptoms of dry eye.