If you've ever swam underwater with your eyes open, you have noticed that your eyes sting a bit afterwards. Unlike many animals, we don't have a third eyelid to protect our eyes underwater, but does that mean we shouldn't swim with our eyes open?
Author
Gunnar Schmidtmann
Associate Professor of Optometry and Vision Science, University of Plymouth
Fortunately, swimming with open eyes is generally not dangerous. However, certain factors must be considered to ensure your safety and comfort.
The stinging or gritty sensation of the eyes is caused by the highly sensitive translucent conjunctiva that covers the white bit and the inner lids of our eyes.
This sensation can be caused by various irritants, depending on the environment. For instance, most public swimming pools contain chlorinated water. Water, including swimming pool water, would be an ideal environment for numerous, potentially harmful microbes, such as bacteria and fungi.
Chlorine or chlorine compounds have antimicrobial properties. These chemicals are commonly added to the water as a disinfectant to minimise the number of harmful microbes and to prevent the spread of infectious waterborne diseases. Prolonged exposure to these substances or their byproducts can in some people lead to irritations and sometimes lead to more serious conditions like conjunctivitis - commonly known as pink eye.
Conjunctivitis is an inflammation of the conjunctiva caused by either a bacterial, viral or, occasionally, fungal infection. One sign of inflammation is the redness, caused by an increased blood vessel diameter and hence increased blood flow initiated by the immune system to fight the infection. This causes the pinkish, reddish discolouration.
Another sign of inflammation is pain, which is often felt as a stinging sensation or grittiness. Conjunctivitis usually clears up on its own. The most common viral conjunctivitis usually does not require any treatment and typically resolves in one to two weeks. Antibiotic eye drops might be required in the case of bacterial infections.
Frequent swimming can also cause changes in the tear film and lead to a condition called dry eye, which is characterised by a gritty sensation or blurred vision.
Salt water
But what about swimming in salt-water pools or the oceans?
Salt water is less likely to irritate compared with chlorinated water, but it can still be uncomfortable for swimmers. The relatively high concentration of salt content in seawater can make eyes feel dry and gritty, but it is generally of no concern unless the water quality is poor.
Poor water quality in the sea, but also rivers and lakes increases the risk of eye infections and other health issues.
Swimming with open eyes is unlikely to cause serious harm, but it is always advisable to take precautions to maintain eye health and prevent discomfort. Using swimming goggles can protect your eyes from chemicals, salt and potentially harmful microbes, providing a barrier and allowing you to see clearly underwater.
Rinsing your eyes with clean water or saline solution can help remove any irritants. Good eyelid hygiene is also recommended.
It is important to avoid swimming in polluted water. Steer clear of water that looks dirty, smells bad, or is known to have high levels of bacteria or pollution. Finally, if you experience prolonged redness, pain, or vision changes after swimming, seek medical advice.
Gunnar Schmidtmann does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
