December Newsletter: Does Dehydration Affect Your Eye Health?

Woman drinks water on the beach.

Does Dehydration Affect Your Eye Health?

Wondering why your eyes feel dry and irritated when you're dehydrated? Fluid loss can cause a variety of uncomfortable symptoms, ranging from dizziness to blurred vision.

Why Is Dehydration So Dangerous?

Dehydration occurs when you lose more water than you take in. Water helps keep organs and tissues healthy and is essential for blood pressure regulation, digestion, and joint lubrication, in addition to good eye health.

Sweating, vomiting, diarrhea, alcohol use, or not drinking enough water are common causes of dehydration. Some medications, like diuretics, can also cause dehydration. Dehydration can creep up on you, particularly if you're sick or spending time outdoors on a hot day.

If you experience thirst, dry mouth, dizziness, confusion, fast heart rate, and other symptoms and don't increase your fluid intake, you could develop kidney problems, seizures, dangerously low blood pressure, organ failure, or death, in severe cases.

Dehydration and Dry Eye

Water keeps your eyes moist and is a key component in the tear film that moistens your eyes. When your fluid level drops, your eyes struggle to produce enough tears to lubricate the outside surface of the eye.

If you don't drink enough water throughout the day, your eyes may feel dry and might itch, burn, or look red. You may also feel like something is stuck in your eyes or notice that you're more sensitive to light. Dry eye can be a factor in eyestrain, a condition that causes eye pain, redness, tired eyes, headaches, and blurry or double vision.

Water Keeps Your Vision Sharp

Blurry vision can also occur if your cornea and lens are deprived of water. The cornea and lens work together to focus light on the retina. The cornea is the clear rounded tissue over the iris and pupil, while the transparent lens is located inside the eye behind the iris and pupil. Dehydration can temporarily cloud the cornea and lens, change the shape of these structures, and affect the sharpness of your vision and your focusing ability.

The light-sensing tissues in the retina may also be affected by dehydration. The retina transforms light rays into electrical signals used by the brain to produce the images you see. Tiny blood vessels in the retina provide a constant flow of blood, nutrients, and oxygen. Unfortunately, dehydration can lower blood volume, reducing the amount of nutrients and oxygen that reach the retina.

Lack of water may also affect the aqueous humor and vitreous humor and cause blurred vision. The aqueous humor is a thin fluid that nourishes and cornea and lens and helps wash away dust, debris, and pollen from the front of the eye. The vitreous humor is the gel that fills the space between the lens and retina and gives the eye its round shape. The vitreous humor begins to shrink when you're dehydrated, which could possibly increase your risk for floaters. Floaters are wispy shadows that form when strands of the vitreous humor stick together.

Dehydration may also play a role in cataract development, diseases that affect the blood vessels in the retina, and refractive changes, according to a study published in Clinical and Experimental Ophthalmology. Refractive changes could cause nearsightedness or farsightedness to worsen.

What You Can Do to Avoid Dehydration

These tips will help you avoid eye health issues caused by dehydration.

  • Drink Plenty of Water. Most people need to drink four to six cups of water per day, according to Harvard Health Publishing. The fluids you take in from foods and other beverages counts toward your daily total. The amount of water you'll need varies depending on the air temperature, your activity level, and your health conditions and medications.
  • Remind Yourself. Set a timer or use the alarm feature on your phone to remind yourself to hydrate. Drinking water with breakfast and meals is a simple way to ensure you get the water you need.
  • Pay Attention to Dehydration Signs. Drinking when you're thirsty or your mouth feels dry will rehydrate you and help you avoid eye health issues.
  • Know When to Increase Your Fluid Intake. Sweating depletes fluids in your body on hot days. Don't venture outside without a bottle of water. If a prescription medication causes frequent urination, ask your doctor if you should drink more water to compensate.

Are you struggling with dry eye or other eye health issues? If increasing your water intake hasn't helped, call our office to schedule a visit with the ophthalmologist


PubMed: Clinical and Experimental Ophthalmology: Hydration, Fluid Regulation and the Eye: in Health and Disease, 6/19/2015

Harvard Health Publishing: How Much Water Should You Drink?, 5/22/2023

All About Vision: How Dehydration Can Impact Eye Health and Vision, 4/18/2023

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