The natural defence of tears

Are Tears Really Important?

We tend to think of tears as something that only appears when we are upset, but they are working quietly every single moment your eyes are open. Tears are necessary for maintaining the health of the front surface of the eye and for providing clear, comfortable vision. Without them, even simple tasks like reading or looking at a screen would quickly become painful.

What is the tear film made of?

Every time you blink, a thin layer called the tear film spreads across the surface of your eye. Far from being plain water, it is a carefully balanced structure made up of three layers that work together:

• The oily (lipid) layer sits on the outside and slows down how quickly your tears evaporate, keeping the surface stable between blinks.
• The watery (aqueous) layer is the thickest part. It hydrates the eye, washes away debris and delivers oxygen and nutrients to the surface cells.
• The mucus (mucin) layer lies closest to the eye and helps the tear film spread evenly and stick to the surface.

When all three layers are in balance, your vision stays sharp and your eyes feel comfortable.

What does the tear film do?

Ever wondered what the function of a tear film is?

• It keeps the ocular surface lubricated, protecting the eye against injury
• It serves as a mechanism for removing debris on the ocular surface
• It aids metabolism, secretion and waste removal from the eye
• It provides nutrition to the anterior surface cells
• It exerts antibacterial action, protecting against infection

When tears aren’t enough

When your eyes don’t make enough tears, or the tear film doesn’t work the right way, you can develop dry eyes. Severe dry eyes may damage the front surface of the eye, raise the risk of infection and impair vision. Common triggers include long hours on screens, air-conditioned environments, ageing and contact lens wear.

If your eyes often feel gritty, tired or irritated, it may be a sign that your natural defence needs a helping hand. You can learn more in our guide to all about dry eyes, or read why overworked eyes can lead to dryness. Preservative-free lubricating eye drops can help top up the tear film and keep your eyes feeling fresh throughout the day.