I love a film that makes me cry or even watching a great sports performance can get the tears rolling (ice skating currently seems to have me dabbing at my eyes). Have you ever wondered why water comes from our eyes when we’re sad or tired or frustrated? Interestingly crying (or lacrimation) is one of the most unique and perplexing of human behaviours and it is the only physiological function that is unique to humans. The physical consistency of tears themselves is also complex. There are three different kinds. But what is the purpose of turning on the waterworks? It all depends on what caused them.

There are three types of tears. Basal, reflex and emotional.

Basal tears:

Basal tears are the ones in our eyes all the time that serve to protect, nourish and lubricate the eyes. These tears are chemically different from other types of tears.

• Constantly produced

• Keep dirt and debris away

• Made up of three layers: mucus layer which keeps tears fastened to the eye, an aqueous layer which keeps in hydration and keeps out invasive bacteria, and an outer lipid layer which keeps the surface smooth.

Reflex tears:

Reflex tears appear in large quantities to protect the eye from irritants such as wind, smoke, or the chemical “syn-propanethial-S-oxide” in onions.

• Wash away harmful substances

• Released in large amounts

• The aqueous layer contains antibodies to stop microorganisms

Emotional tears:

Emotional tears are unique to humans and are the most mysterious kind of tears. Scientists don’t know exactly why we emotionally cry but there are various theories. One theory according to a study out of Vassar College suggests tears developed as a silent signalling system to let others respond to us when we are vulnerable without alerting predators. Others believe it’s a way to elicit compassion. There’s also the argument that a good cry alleviates stress - 85% of women and 73% of men report feeling better afterwards. Lastly, there’s the possibility that tears help build strong communities by eliciting empathy and therefore closer relationships necessary to living in a complex society.

• Stabilize mood

• Contain high levels of stress hormone ACTH

• Contain encephalin–an endorphin and natural painkiller
  

Now the next time you’re watching the John Lewis advert, you will know that your eyes are welling up for a purpose and can reflect on how the tears are an example of the incredibly intricate systems that go into making us humans who we are.

I hope this blog post has been of interest and I look forward to welcoming you in practice again soon.

Lucinda

Discover our other eye care blogs