How dehydration impacts your eyes

Medically reviewed by Sharon Copeland on 04 May 2021

Dehydration can cause numerous effects on your immediate health and wellbeing, whether it’s headaches, sleepiness, cramps, light-headedness or even kidney stones. But what you might not know is that as your body dehydrates, so do your tear ducts – which could result in dry eyes, blurry vision and problems to your vision and overall eye health. It is therefore important to drink a good amount of fluid in order to properly hydrate, especially if you do a lot of physical activity. Your body weight is likely to decline when you exercise as your body loses fluid at a rapid rate.

Symptoms of dehydration

Symptoms of dehydration are varied. You might experience a dry mouth, thirst and dry skin and people who are chronically dehydrated may experience a higher blood pressure. Dry eye is another symptom of dehydration and can cause a wealth of issues including eye pain, vision distortion, red eyes and more.

What is dry eye?

Dry eye is when your tear ducts are no longer producing sufficient tears, or some of the tear components may be lacking, causing the tears to break up prematurely and therefore leaving the eyes dry. As a result, eyes aren’t producing the moisture they need to stay hydrated.

Being dehydrated can cause dry eyes and blurry vision as your body will prioritize using water for processes more important such as maintaining the circulation of the brain.

This often causes irritating and uncomfortable symptoms, such as grittiness, redness and blurred vision.

Can my contact lenses become dehydrated?

As your contact lenses rely on the natural moisture of your eyes to remain hydrated and comfortable to wear throughout the day, they’ll start to dry out if your eyes become dehydrated.

It’s also interesting to note that even though high water lenses allow a lot of oxygen through, they could also be unsuitable for dry eyes as they’re thicker. The best lenses for dry eyes are low-mid water lenses.

Can dehydration cause blurred vision?

Dehydration and vision distortion are often closely associated. This is because dehydration causes eye strain which in turn can lead to blurry vision and blurred vision headaches. Tired eyes are also a symptom of eye strain which can lead to vision distortion. You can get eye strain from spending excessive amounts of time in front of a screen as you tend to blink less during the process. Producing tears by blinking helps to keep your eyes lubricated and hydrated. For this reason, it may be a good idea to use eye drops such as our Blink Intensive Tears Plus or Systane Hydration.

My eyesight is getting worse all of a sudden

Blurry vision can be a sign of more severe eye problems, especially if it comes on suddenly. Eye problems and diseases causing blurry vision include having a detached retina, eye herpes, cataracts or an inflammation of the optic nerve. These can lead to a permanent loss of vision. It is therefore very important to see an eye doctor if you experience this.

If you are over 60 and experience blurry vision all of a sudden in one eye, it could be possible that you have developed a macular hole in your retina. Macular holes are not a result of dehydration.

Dehydration can also cause eye floaters

Eye floaters are spots in your vision and are mostly caused by age related changes, however, dehydration can also be a cause. Eye floaters occur when the gel like substance in your eye known as the vitreous humour loses shape. As it is made of 98 per cent water, dehydration can cause this to happen as the proteins solidify instead of remaining dissolved. 

How can I hydrate my eyes?

Drinking plenty of water will help prevent dry eye and irritation. Maintaining healthy eyes by drinking water can also prevent eye floaters and flush out the toxins that form them, thus getting rid of them.

Other measures you can take to prevent your eyes becoming dehydrated include taking regular breaks from sitting at the computer or watching TV, as use of these screens often reduces the amount that you blink, therefore increasing the chance of dry eye. Remember to practice the 20-20-20 rule with digital screens, every 20 minutes look 20 feet into the distance for 20 seconds.

It’s also recommended to avoid using air conditioning, fans or indoor heating wherever possible, to keep the air from becoming too dry and causing your eyes and contact lenses to dry out. An alternative way to protect your eyes from this is to introduce a humidifier to your home or workplace to counter the effects of these influences.

The use of eye drops/gels specially designed to prevent eyes from drying and offer fast, effective relief is also advised.

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