Tears are necessary to give you good vision, keep your eyes healthy and protect them from irritants.

Emotional tears – caused by strong feelings of happiness, sadness or pain – are different from the tears produced, for example, from peeling an onion, and may contain hormones and chemicals released by the body.

Crying might make your eyes red and puffy, but they won’t affect your eyesight – you can’t literally ‘cry your eyes out’!

There are three types of tear, with each containing a combination of water, fats, sugars and proteins. They all play an important role in protecting and preserving the condition of our eyes:

Basal Tears

This is the liquid constantly present in the eye, which ensures that the cornea is always wet and nourished.

The cornea itself has no blood vessels, and is dependent upon the tear film for its oxygen supply, which it gets from the air when the eye is open. The thin layer of liquid also smoothes out irregularities and creates an even surface of good optical quality, which is re-formed every time you blink.

The washing action of the liquid tear film reduces the ability of bacteria to adhere to the surface of the eye, while the antibiotic proteins in the liquid help kill them off. Basal tears also act as a lubricant to limit the impact of friction on the eye caused by movement of the eyelid.

Reflex Tears

These tears are essentially the same as basal tears, but are a result of an increase in the level of liquid the eye produces in response to a sudden external stimulus. This could be due to the irritation of the eye by foreign particles, such as dust, or from irritant substances like onion vapours, tear gas or pepper spray. By creating a sudden increase in the level of basal tears, this reflex serves to immediately wash out irritants that may have come into contact with the eye, and makes your eyes ‘water’.

Emotional Tears

Crying due to pain, grief, anger or happiness, is often accompanied with spasms of the whole body and interrupted breathing patterns.

Tears brought about by emotion have been shown to contain a different chemical make-up than to those of basal or reflex tears in that they have more protein.  A high level of emotions can trigger the parasympathetic branch of the autonomic system (the part of the body that acts as an unconscious control system), and will cause the glands near your eyes to produce tears. One researcher has suggested that by excreting these hormones in the form of tears, the body is helping you feel calmer and less emotional afterwards.


This is the name for an overflow of tears. This can be reflex or emotional (as above) but can also be a result of a drainage failure, where the small draining holes in your eyelids fail to drain the tears away efficiently into your nose.  This can lead to leakage and an excess of water on the surface of the cornea, which can cause a ‘watery eye’ and blurring of vision. It can be made worse by cold winds or dry conditions.

The video below should be viewed in conjunction with the text beneath it and preferably watched while your optometrist discusses it with you.

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  • When we blink, the tears lubricate, nourish and protect the front of the eye.
  • Tears have three main components: The lachrymal gland produces a watery component
  • … glands in our eyelids produce an oily component, while other cells produce a mucus.
  • These mix together to create a film which covers the white of the eye and the cornea.
  • When we blink, the film is wiped across the eye by the eyelids.
  • If insufficient tears are produced or the constituents are out of balance
  • … it can result in sore, dry eyes.
  • Wearing glasses or sunglasses can help to reduce tear evaporation.
  • Instilling artificial tears can also help.
  • In some cases, the tears can be kept in the eye for longer by plugging the tear ducts.