Eye Health Central

How Dehydration Impacts Your Eyes

Hydration is essential for our eyes

Water is fundamental to the proper functioning of every cell and organ in your body, and your eyes are no exception. Maintaining adequate hydration is essential for overall health, but have you ever thought about the effects of dehydration on your eyes?

1. Understanding Dehydration:

Dehydration happens when the body loses more fluids than it takes in, preventing it from carrying out its regular functions. This imbalance can happen when you’re not ingesting enough water or fluid intake, you’re sweating excessively, you have a certain medical condition, or you’re consuming too much of certain diuretic substances like caffeine and alcohol.

How dehydration effects the eyes

2. Dry Eye Syndrome:

One of the most noticeable symptoms of dehydration is dry eyes. Although over-hydration can also potentially result in a few eye diseases there is no evidence between upping water intake in non-dehydrated people and decreased dry eye disease. Our eyes rely on adequate moisture to produce tears, which keep them lubricated and make sure we have clear vision, dehydration is still a factor when it comes to dry eye syndrome. When your body is dehydrated:

  • Tear production can decrease! This leads to dryness and discomfort.
  • The quality of your tears can be affected. Healthy tears have a delicate balance of water, mucus, and oil. Dehydration can disrupt this balance, causing evaporative dry eye, where your tears will evaporate too quickly because of the lack of water content.

3. Reduced Vision Quality:

Your eyes need adequate hydration to function optimally, if you’re dehydrated this can lead to:

  • Blurry vision: With reduced tear production, the eyes cannot maintain a smooth, clear surface making your vision blurry.
  • Slow reaction time: A lack of proper lubrication can slow down the reflexes of your eyes, leading to a slower response to stimuli.

4. Eye Strain and Fatigue:

Dehydrated eyes have to work harder to focus which ultimately results in strain. This eye strain can cause:

  • Headaches: If you have strained eyes, you most likely will start to have tension headaches.
  • Fatigue: Your eyes feel tired and heavy, even after a very short period of reading or computer use.

5. Decreased Pressure Regulation:

Adequate fluid levels are essential for maintaining intraocular pressure (the pressure inside your eyes). Dehydration can cause fluctuations in this pressure, long term dehydration might increase your risk for conditions like glaucoma if you are predisposed to it.

6. Impact on Eye Health in the Long Run:

Chronic dehydration doesn't just lead to temporary discomfort. It can have long-term impacts:

  • Reduced tear production: Over time, chronic dehydration can affect your eye's ability to produce tears which can lead to persistent dry eye syndrome.
  • Increased risk of eye conditions: Chronic dry eyes can lead to you having complications like infections, corneal ulcers, and vision impairment.

7. Eye Symptoms Related to Dehydration to Watch Out For:

If you're dehydrated, your eyes might exhibit the following symptoms:

  • Stinging or burning sensation
  • Sensitivity to light
  • Redness
  • Blurry vision
  • The feeling of something being stuck in the eyes
  • Discharge or mucus in and around the eyes

8. How to Protect Your Eyes from Dehydration:

  • Stay Hydrated: The simplest way to prevent dehydration-related eye issues is for you to drink sufficient water every day. The typical recommendation is 8-10 glasses, but this can vary depending on your needs, the climate you live in, and your activity levels.
  • Limit Diuretics: Minimise the consumption of diuretics like caffeine and alcohol as these increase your fluid loss.
  • Use Artificial Tears: If you're prone to dry eyes, consider using artificial tears to keep your eyes lubricated. Whilst this won't help with dehydration, it may relieve your dry eyes, however, evidence has shown that it doesn’t help all individuals.
  • Protect Your Eyes: In windy or dry climates you should consider wearing sunglasses to reduce tear evaporation.
  • Take Regular Breaks: When doing tasks that require intense focus, like reading or using the computer, follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for at least 20 seconds. 


While dehydration's impact on our body is often discussed such as fatigue, muscle cramps, and cognitive functions, its effects on the eyes can be serious but are discussed less frequently. By understanding the impacts, we pointed out above and taking proactive measures, you can ensure that your eyes remain healthy and comfortable. So the next time you feel thirsty, remember that your eyes are thirsty too. Staying hydrated is key for several reasons including clear vision.  

Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 4 Oct 2023, Last modified: 20 May 2024