Dehydration and Eye Health: How to Prevent Dry Eyes
Most people realise water is important for human health. After all, 50 - 65 per cent of an adult’s body is made from water. What many of us forget, however, is that water is an essential ingredient for maintaining the health of our eyes. The eye is made of three chambers — the largest of which is the vitreous chamber. This is filled with a clear, colourless fluid called the vitreous humour, which helps your eye keep its shape and the retina in place. This vitreous humour is made of 99 per cent water, with the rest being a mixture of collagen, proteins, salts and sugars. As such, when we become dehydrated, not only can this have a significant impact on our bodies, but also on our eyes. To help you understand how dehydration affects the eyes a little better, and how to prevent them, we’ve put together this helpful guide.
What is dehydration?
Maintaining a healthy water level in the body is a complex process involving your kidneys and substances in the blood called electrolytes that regulate water balance at a cellular level. Every day you lose an amount of water through things like urine, sweat and exhaling. But when you lose or use more water than you take in, it can leave you dehydrated. During the very early stages of dehydration, you probably won’t experience any symptoms. However, when you become mildly or moderately dehydrated you may experience a number of symptoms including dry mouth, tiredness, muscle cramps and dizziness. If mild dehydration progresses to severe dehydration, the symptoms can become more serious, including low blood pressure, confusion, loss of consciousness and shock. Meanwhile, if you have prolonged or repeated bouts of dehydration it can lead to urinary tract infections, kidney stones as well as kidney failure.
How does dehydration affect the eyes?
Where your eyes are concerned, being dehydrated – even mildly – can mean you won’t be able to produce enough tears to lubricate them. While crying can produce visible tears, your eyes are constantly producing fluid for your tear film, which helps make sure the transparent front part of the eye – the cornea – stays wet and supplied with oxygen. Each time you blink, your eyelid distributes tear fluid across your cornea. However, when you’re dehydrated and not making enough tears, it can make your eyes feel dry, tired, sore and irritated.
Studies also suggest that dehydration can lead to dry eye syndrome. For instance, in one study published in Investigative Opthalmology & Visual Science, researchers found that those diagnosed with dry eye syndrome had a higher plasma osmolality (level of water in the blood) compared with those who didn’t have dry eye. According to the researchers, their findings indicate that whole-body hydration is an important consideration in dry eye.ii There may be other ways in which dehydration affects vision too. Experts from the Journal of Clinical & Experimental Opthalmology note that owing body hydration status may affect the health of your vision. By reviewing the evidence looking at hydration and major common eye diseases, they found dehydration may be associated with the development of dry eye syndrome, as well as vision problems such as cataracts, refractive changes and retinal vascular disease.iii
How to prevent dry eyes
While dry eye can be irritating and uncomfortable, there are a number of practical steps you can take to prevent dehydration and soothe dry eyes.
Drink more water
Keeping your fluid levels topped up on a regular basis will help prevent dehydration. According to the NHS, around 1.2 litres of fluid a day – that’s about six to eight glasses – is enough to stop you from becoming dehydrated (but you may need more if you’re staying in a hot country). While plain water is the best option, a number of other choices include milk, tea and coffee, sugar-free squash and a limited amount of fruit juice, as it’s naturally high in sugar (the NHS recommends a maximum of 150ml of fruit juice daily).
Eat hydrating foods
Some of the water we take in also comes from food. Fruit and vegetables are the best hydrating foods, with melons, cucumber, lettuce, celery, tomatoes, strawberries and spinach all made up of more than 90 per cent water.
Invest in a humidifier
Central heating and air conditioning can produce dry air, which can make your eyes feel uncomfortable. If you’re more susceptible to the effects of dry air, using a humidifier to put some moisture back into the air around you may be useful.
Use lubricating treatments
There is a range of products you can buy over the counter at pharmacies that are designed to help soothe dry eyes. Often called artificial tears, these include drops that replenish the water in your tear film.
Nourish your eyes
Alongside increasing your water intake, researchers have found that nutrient may also help to improve dry eyes. Two nutrients that have been found to help with dry eye symptoms are sea buckthorn oil and fish oils such as cod liver oil and krill oil because they are rich in omega 3s. There is evidence to suggest that taking sea buckthorn oil may help reduce tear film osmolarity, thought to be a cause of dry eye syndrome.iv Meanwhile, studies suggest that the omega-3 fatty acids found in fish oil may also have a role in treating dry eye syndrome, though the benefits may only apply to people who have symptoms caused by eye conditions such as blepharitis and meibomian gland disease.v
With these simple steps, you could be a stage closer to more hydrated, healthier eyes. Want to discover more information on a range of common eye conditions? Take a look around our Vision Health Hub.
Dry Eye Syndrome. NHS Choices. Available online: https://www.nhs.uk/conditions/dry-eyes/
Walsh, N.P., et al. Is Whole-Body Hydration an Important Consideration in Dry Eye? Investigative Ophthalmology & Visual Science. September 2012. Vol.53, 6622-6627. Available online: https://iovs.arvojournals.org/article.aspx?articleid=2127960
Sherwin, J.C., Kokavec, J., Thornton, S.N. Hydration, fluid regulation and the eye: in health and disease. Clin Exp Ophthalmol. 2015 Nov.43(8):749-64. Available online: https://www.ncbi.nlm.nih.gov/pubmed/25950246
Larmo, P.S., Jarvinen, R.L., et al. Oral sea buckthorn oil attenuates tear film osmolarity and symptoms in individuals with dry eye. J Nutr. 2010 Aug.140(8):1462-8. Available online: https://www.ncbi.nlm.nih.gov/pubmed/20554904
Rahul, B., Prachi, K., et al. A randomized controlled trial of omega-3 fatty acids in dry eye syndrome. Int J Opthalmol. 2013.6(6):811-816. Available online: https://www.ncbi.nlm.nih.gov/pubmed/24392330