Dry eyes, medically known as keratoconjunctivitis sicca, is a common condition affecting millions. It occurs when the eyes do not produce enough quality tears or when tears evaporate too quickly, leading to discomfort, visual disturbances, and potential damage to the eye’s surface. Symptoms often include a stinging, burning, or scratchy sensation, a feeling of having something in the eye, and sometimes excessive watering as a reflex response to irritation. The connection between this ocular discomfort and the body’s overall hydration status is a question frequently asked.
The Direct Connection to Systemic Hydration
Systemic dehydration is a contributing factor to dry eyes because the body prioritizes fluid allocation to maintain the function of vital organs. When a person is dehydrated, the body conserves water by reducing fluid output in non-critical areas, which includes tear production. This reduction directly impacts the volume of tears available to lubricate the eye surface.
Tears are produced by the lacrimal glands, and their primary component is water, making tear volume highly dependent on the body’s water reserves. Studies demonstrate a direct and measurable link between fluid intake and tear production. A lack of sufficient water intake can certainly worsen or induce symptoms of ocular dryness.
The Science of Tear Film and Fluid Balance
Tears form a complex, three-layered structure called the tear film, consisting of a lipid (oil) layer, an aqueous (water) layer, and a mucin (mucus) layer. The middle aqueous layer, which is the thickest and makes up over 90% of the tear film volume, provides moisture and nutrients to the eye surface. This layer is the part most directly affected by systemic hydration.
Dehydration can decrease the volume of the aqueous layer, which leads to a higher concentration of salts and electrolytes in the remaining tear fluid, known as tear hyperosmolarity. This hyperosmolarity damages the eye’s surface cells and triggers inflammation, destabilizing the tear film and creating a cycle of persistent dryness. The maintenance of proper fluid balance is directly linked to the stability and health of the aqueous tear layer.
Other Common Causes of Ocular Dryness
Many factors unrelated to systemic dehydration can cause or contribute to dry eyes. Environmental conditions like low humidity, wind, smoke, or prolonged exposure to air conditioning accelerate the evaporation of the aqueous layer. Extended periods of screen time significantly reduce the rate of blinking, causing tears to evaporate before they can be replenished.
Certain medications are known to decrease tear production, including antihistamines, decongestants, some blood pressure medications, and antidepressants. The natural aging process is a factor, as tear production tends to diminish in individuals over 50. Other medical issues, such as meibomian gland dysfunction and autoimmune diseases like Sjögren’s syndrome, can also be underlying causes.
Immediate Relief and Long-Term Prevention
Immediate relief for dry eyes often comes from using over-the-counter artificial tears, also known as lubricating eye drops, which supplement the natural tear film. For frequent use, choosing preservative-free drops is advisable to prevent irritation. Avoid eye drops marketed specifically for “redness,” as these can cause rebound redness and worsen dryness over time.
Long-term prevention should incorporate both hydration correction and lifestyle adjustments. Increasing daily water intake is a simple and effective step that helps ensure the body has sufficient fluid for tear production. Using a humidifier adds moisture to the air and slows the rate of tear evaporation. Adopting the “20-20 rule” during screen time can help refresh the tear film and reduce eye strain.