Tears: A Research On Origin, Functions And Importance Of The Human Tears

Tears are a universal language, transcending words to convey varying degrees of emotions that touch the very core of our humanity. From the joyful tears of a wedding day to the sorrowful tears of loss, tears have been a timeless expression of the human experience. Research entails that beyond their emotional significance, tears also play a vital role in maintaining the health and function of our eyes, protecting them from infection and keeping them lubricated.

Tears aren't simple. They are complex creations of water, mucins, oils and electrolytes; funny huh. They also possess some protective bacteria fighting substances that help reduce our risk of getting eye infections. It might interest you to know that the word 'Machozi' means tears in Swahili. 

In the action of blinking, the upper eyelid sweep tears across the surface of the cornea, down towards the inner corner of each eye. The tears drain through a small opening in the eyelid called the puncta, found in each eyelid. The tears flow through the puncta into the nasolacrimal duct, a carnal that drains excess tears into the nasal passage (which is why, when you cry, you also need to blow your nose).

Tears function in many and essential ways. For the cornea, they provide a smoother optical surface, so that our vision remains clear; the cornea is also kept properly moisturized and rich in oxygen. For the eye in general, tears also act as 'wiper fluid ', allowing the eyelids to wash the eye free of debris with every blink.

Tearing - by the way, the word we're using rhymes with hearing, not herring - isn't just crying, although that's certainly one reason for tearing. When eye doctors use the term, it simply means 'making too many tears' - in other words having watery eyes. Tearing could be classified into two significant types: the first basic tearing, this is normal involuntary tearing, which helps maintain the eye. The second, reflex tearing, is a reaction to stimulus, such as a foreign body in the eye or a strong emotion (happy, sad or surprised).

Tears, believe it or not, are layered. I could go on and on about the innermost layer which contains mucins, which allow tears to adhere to your eye and coat it evenly. And then to the production of mucins by tiny factories named 'goblet cells' in the conjunctiva (the clear covering over the "white" of your eye) and inside your eyelids. There also exists the middle layer, which makes up about 90 percent of the tear 'mainly water with just a pinch of salt'.

Most of this watery layer is produced by the lacrimal glands , located just above and outside each eye. It would evenly interest you to know that as a backup system, our eyes are also equipped with accessory glands, which provide extra water.

The outermost layer which contains fatty oils, called 'lipids', which slow the evaporation of the watery layer and thus keep tears in our eyes longer, just as a coating of lotion helps skin retain moisture. These oils are produced by the 'Meibomian glands' on the edges of the eyelid, just behind the lashes and to which a reduction in any of these layers can lead to dryness.

When your eye is irritated, the reflex tearing mechanism causes the lacrimal glands to produce water - the goal of washing away the irritants. If your eye becomes significantly irritated from dryness, say or allergies then reflex tearing will start. Reflex tears, designed to solve temporary problems, containing much more water than basic tears; they're low in mucins and oils, so they don't do much to lubricate the eye.

Your eyes will get very watery because the quality of these tears is so poor, the excess water won't really help with the dryness. But simply adding a drop of an artificial tear substitute to your eyes when they are watering excessively can change everything. 

Reference: The Eye Book. G

ary H. Cassel, MD.