The composition of your tears is complex
Your tears are made up of three layers: a base mucin layer, a central aqueous layer and an outer oily layer, together they form an advanced piece of liquid engineering to keep your eyes healthy and your vision sharp. The latest thinking suggests these layers are not rigidly divided but instead are in a state of flux and mix with one another. The role of your tears is multifaceted and ranges from simple lubrication to providing nutrition and fighting infection.
Where do your tears come from?
Your tears are produced by a series of special glands. The main tear or lacrimal glands can be found above each eyeball. These two small glands are continuously producing tears which travel down a series of ducts in the eye lids to your eyes. The tears are spread over the eye with each blink, the eyelid acting as a small windscreen wiper. Eventually your tears either evaporate or drain out via the small duct at the corner of your eye near your nose – it is called the puncta.
The oily component comes from a separate set of glands called the meibomian glands which are located in the eye lids. Again, the meibum flows into the eye as we blink to provide that protective outer layer.
There are 3 different types of tears
This incredible fluid is even more complex than first thought. You actually produce three different types of tears which have different functions and compositions.
1. Basal tears which are the ones you produce all the time for the reasons of clear vision and eye health. These are rich in salts such as sodium and potassium chloride.
2. Reflex tears are produced by your body as a response to an irritant, such as smoke or vapour from an onion, This is a protective response to flush away potential risks to your eye. Cleverly these tears have more antibodies than usual in another clever way to keep your eyes healthy
3. Emotional tears. These are the tears you produce in response to deeper feelings produced: - like when watching a sad movie, experiencing a joyful event or the pain of stubbing your toe! These tears are truly amazing and scientists have identified increased level of certain stress hormones and chemicals which are not found in either basal or reflex tears.
Have a good cry – it’ll do you good
Whether it is reflex tears washing away irritants or emotional tears helping to destress us crying is generally thought of as a good thing. Your emotional tears have a particular role as they signal to those around us of how you feel and are an important part of our sophisticated human communications, in fact humans are thought to be the only species which cries. But scientists also believe that emotional tears are not just about communication, they also bring physiological benefits such as releasing stress hormones from the body – you do really feel better after a good cry!
Looking like after your tears
As you get older you will tend to produce less tears or tears of a poorer quality. This can make you more susceptible to tired, sore or dry feeling eyes. But there are some simple things you can do to look after your tears. Try to avoid drying environments by turning down the air-conditioning and central heating, drink plenty of water, resting your eyes regularly from screen work, making sure you include oily fish rich in omega-3 in your diet and avoid using make-up with chemical irritants in. This might not aways be possible so make sure you keep some artificial tears at hand, such as HydraMed, to use before dry eye symptoms start i.e. before getting on a flight or at the start of a long day in the office. The Dry Eye Zone offers a range of tried and tested solutions to keep your peepers looking and feeling their best.
If you are experiencing dry, tired feeling eyes then you should ask the advice of your eye care professional.
Sources:
Chang AY, Purt B. Biochemistry, Tear Film. [Updated 2022 Jun 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572136/
American Academy of Ophthalmology. Eye Facts and Science by Reena Mukamal, Reviewed by Dr Devin A Harrison. 21 December 2016
Science Alert. Why Do We Cry? The Chemistry of Three Types of Tears by Bec Crew. 12 May 2015
Why are humans the only animals that cry? By Amanda Smith
Posted 23 Jul 201323 Jul 2013, updated 15 Apr 2014
Juan Murube, Basal, Reflex, and Psycho-emotional Tears, The Ocular Surface,Volume 7, Issue 2, 2009,
Pages 60-66, ISSN 1542-0124, https://doi.org/10.1016/S1542-0124(12)70296-3.