When we speak of tears, it’s always associated with sadness, pain and crying which makes our eyes watery. From a medical perspective, tears are real unsung heroes of overall eye health. They come in different types and contains water, glycerine and other minerals so, let’s have a closer look.
Protector of the Eyes
It’s no surprise that tears offer daily protection to the eyes as the tear film shields the vulnerable eye surface against all sorts of airborne germs, allergens and irritants. An eye tear is composed of three layers namely a mucous layer spread directly on the corneal surface, an aqueous layer made of saltwater and an exterior oily layer which keeps all other eye films intact from evaporation.
Combination of the three layers keep the eyes lubricated, clean and free from harmful bacteria. With every single blink of the eye, tears wash away debris from the eyes while keeping the vision clear and the eye comfortable. This is the reason grit is caked on the eyes while we’re asleep because the gunk isn’t getting cleared out.
The Lipid Layer
This particular layer is concealed by the Meibomian glands right on the eyelid edges thus preventing tear evaporation while covering the exterior surface.
In case the Meibomian gland function drops due to inflammation or natural aging, there would be a decrease in oily substance secretion or, the composition of the secrete may alter which might then resembles wax, glands can be clogged as well.
All of this results in reduced stability of the tears while leading to dry eye syndrome which in medical terminology is known as Meibomian Gland Dysfunction and quite a common anomaly amongst the elderly.
The Aqueous Layer
The aqueous layer contributes to 95% of the tear making and includes various proteins. It’s also responsible to supply essential nutrients to the cornea, prevents bacterial infection and heals the damage. The aqueous layer is released by the lacrimal gland beneath the upper eyelid. Adding to it, the mucus mucin (mucin secretor) is released by the goblet cells on the eye surface helps in uniform distribution of the tears across the eye surface. Medical research has also concluded that mucin plays a crucial role in tear stability.
Tear Generation & Drainage
The tear film refreshes constantly that can be affected at times post vitrectomy surgery for better and effective function. Eye glands continuously generate tears whereas ducts in the deeper inner corners of the eye drain away excess tears right into our nose. Now we know the reason behind runny nose every time we cry or sneeze.
Feel Better with Tears
The aqueous layer of the tear film comprises basal tears but, each time when we cry or the tears are released from the eyes, they come in two different types namely: reflex and emotional. That said, reflex tears are simply excessive basal tears that flush out a foreign object from thus helps it clean. These are also released when we chop onions or inhale something pungent or spicy that sting in the eyes.