Scratchiness, burning, or persistent redness in the eyes is often referred to as dry eye syndrome. This discomfort arises when the eyes do not produce enough tears or when tears evaporate too quickly, irritating the ocular surface. When these symptoms appear, many people consider increasing their water intake to improve overall body fluid levels. This article explores the connection between systemic hydration and the moisture balance of the eyes.
The Link Between Dehydration and Eye Moisture
Systemic dehydration, which occurs when the body loses more fluid than it takes in, can contribute to dry eye symptoms. The body prioritizes water distribution, sending available fluids to organs like the brain and heart before allocating resources to less necessary areas. When water intake is insufficient, the supply available for mucous membranes and tear production is diminished.
The eyes rely on the lacrimal glands to produce the watery component of tears, requiring adequate overall body fluid to function optimally. Reduced hydration decreases the volume of fluid secreted by these glands, affecting the quantity of tears available to coat the eye. This decreased tear volume is a primary mechanism behind aqueous-deficient dry eye. Individuals with dry eye often exhibit higher plasma osmolality, indicating suboptimal whole-body hydration.
Understanding the Tear Film Structure
Tears are not simply water but a complex, three-layered structure known as the tear film, which lubricates, nourishes, and protects the ocular surface. The innermost mucin layer allows tears to adhere to the eye’s surface, which is otherwise water-repelling. The outermost lipid (oil) layer, secreted by the meibomian glands, slows the evaporation of the underlying watery component.
The aqueous layer is sandwiched between these two layers, making up the largest part of the tear film and composed mostly of water, electrolytes, and protective proteins. This layer is the component most affected by systemic hydration status. When the body is dehydrated, the aqueous layer becomes deficient, reducing overall tear volume.
Insufficient water in the aqueous layer increases the concentration of salts and solutes in the tears, a condition known as tear hyperosmolarity. This hyperosmolar, or saltier, tear film causes irritation and inflammation on the eye’s surface. The resulting instability leads to faster evaporation and damage to corneal and conjunctival cells, creating a worsening cycle of dryness.
Non-Hydration Related Causes of Dry Eyes
While fluid intake plays a part, dry eyes are a multifactorial condition, meaning many other elements disrupt tear film stability. Environmental factors are major contributors, including exposure to high wind, low ambient humidity, and the direct flow of air conditioning or heating vents, which increase tear evaporation. Smoke exposure and high altitudes can also exacerbate feelings of dryness.
Extended periods of screen time significantly contribute because the blink rate decreases by up to 50% during focused viewing. Infrequent blinking prevents the tear film from being adequately spread, leading to localized dry spots. Other causes include aging, which decreases tear production, and hormonal changes, particularly in women after menopause.
Certain systemic medications can induce dry eyes by altering tear composition or reducing tear secretion. These include common drugs such as antihistamines, decongestants, some antidepressants, and certain blood pressure medications. Recognizing these non-hydration-related causes is important for understanding the condition and its potential treatments.
Strategies for Maintaining Ocular Hydration
Addressing dry eye symptoms involves internal and external strategies beyond simply drinking a large amount of water at once. Maintaining a steady intake of fluids throughout the day helps sustain the necessary fluid balance for consistent tear production. Consuming water-rich foods, such as watermelon, cucumber, and oranges, also complements fluid intake and supports eye health.
Environmental modifications can reduce evaporative tear loss. Utilizing a humidifier, especially in heated or air-conditioned indoor spaces, is helpful, as is positioning fans or air vents so they do not blow directly onto the face. When working at a computer, practicing conscious blinking and implementing the 20-20-20 rule helps re-lubricate the eye surface.
For immediate relief, over-the-counter artificial tears can supplement the eye’s natural moisture. Some advanced artificial tears are hypotonic, meaning they have a lower salt concentration to help rebalance the hyperosmolarity of dry tears. Supplementing the diet with Omega-3 fatty acids can also support the meibomian glands, improving the lipid layer quality to reduce tear evaporation.