Dry eyes happen when your tears can’t keep the surface of your eyes adequately lubricated. This can mean your eyes don’t produce enough tears, or the tears you do produce evaporate too quickly. The causes range from everyday habits like screen time to underlying health conditions, medications, and environmental factors.
How Your Tear Film Works
Your tear film isn’t just water. It has three distinct layers, and a problem with any one of them can trigger dry eye symptoms. The innermost layer is a mucus coating produced by specialized cells in the tissue lining your eye. This mucus anchors the watery layer above it to the eye’s surface, acting like a wetting agent that helps tears spread evenly. Without it, tears would bead up and slide off.
The middle layer is the thickest and is mostly water, produced by the lacrimal glands above each eye. It contains proteins, electrolytes, glucose, and oxygen that nourish and protect the eye’s surface while flushing away debris. People with dry eye disease tend to have low levels of key protective proteins in this layer.
The outermost layer is a thin film of oils, including cholesterol, wax esters, and fatty acids. This lipid layer sits at the boundary between your tears and the air, and its primary job is slowing evaporation. When this oil layer is deficient or poor quality, tears evaporate faster than your glands can replace them.
Blocked Oil Glands in the Eyelids
The most common structural cause of dry eyes involves the meibomian glands, dozens of tiny oil-producing glands embedded in your upper and lower eyelids. These glands secrete the lipids that form the protective outer layer of your tear film. When the glands become clogged or the oil they produce turns thick and waxy, less oil reaches the tear surface. The result is faster evaporation of the watery layer underneath, a pattern known as evaporative dry eye.
This blockage, called meibomian gland dysfunction, can happen gradually with age, from chronic inflammation of the eyelids, or alongside skin conditions like rosacea. You might notice it as a gritty, burning sensation that worsens as the day goes on, especially in dry or windy environments.
Screen Time and Reduced Blinking
Every time you blink, you’re respreading tears and oil across the surface of your eye. Between blinks, that moisture steadily evaporates. Research on office workers found that people blink about 22 times per minute when relaxed, roughly 10 times per minute while reading a book, and only about 7 times per minute while looking at a screen. That’s a reduction of nearly 70%.
Fewer blinks means longer gaps where the tear film goes unrefreshed, allowing more evaporative loss with each cycle. Over time, this can initiate a self-reinforcing pattern: the eye surface dries out, becomes inflamed, and that inflammation further destabilizes the tear film. If your eyes feel worst at the end of a workday spent on a computer, this mechanism is likely a major contributor.
Medications That Reduce Tear Production
Several common drug classes can cause or worsen dry eyes as a side effect. Antihistamines, which many people take for allergies, work by blocking a chemical messenger that also plays a role in tear secretion. Antidepressants, blood pressure medications, corticosteroids, and nonsteroidal anti-inflammatory drugs are all linked to dry eye symptoms as well. If your dry eyes started or worsened around the time you began a new medication, that connection is worth exploring with your prescriber.
Autoimmune and Inflammatory Conditions
Dry eyes are a hallmark symptom of several autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues. Sjögren’s syndrome is the most direct example. In Sjögren’s, immune cells infiltrate the lacrimal glands and cause chronic inflammation, steadily reducing tear output. It’s the leading autoimmune cause of dry eye in Western countries.
Rheumatoid arthritis and lupus can both trigger dry eyes as well, through inflammation of the lacrimal glands, the meibomian glands, or both. Sarcoidosis causes lacrimal gland inflammation. Systemic sclerosis leads to scarring (fibrosis) of the tear glands and the tissue lining the eye. Rosacea, a skin condition that causes facial redness, frequently inflames the meibomian glands and disrupts the oil layer of the tear film. If you have persistent dry eyes along with joint pain, fatigue, skin changes, or dry mouth, an autoimmune condition could be the underlying driver.
Hormonal Changes and Sex Differences
Women develop dry eyes at significantly higher rates than men, and the gap widens after menopause. Large epidemiological studies in the United States found that 7% of women over 50 have dry eye disease compared to 4% of men in the same age group. In one study of 384 postmenopausal women, nearly 72% had dry eye disease. Shifting levels of estrogen and androgens after menopause affect tear production, the composition of meibomian gland secretions, and the inflammatory environment on the eye’s surface.
Environmental Triggers
The air around you has a direct effect on how fast your tears evaporate. The Environmental Protection Agency recommends keeping indoor humidity between 45% and 50%. Below that range, your tears lose moisture to the dry air more rapidly. Air conditioning, forced-air heating, and modern building designs that seal tightly for energy efficiency all tend to push indoor humidity below that sweet spot. One study of university staff working in older buildings found that those who perceived their indoor air as dry had measurably less stable tear films.
Wind, high altitude, and smoke exposure accelerate evaporation too. If your symptoms are worse in specific environments, like an office building, an airplane cabin, or a heated bedroom in winter, environmental dryness is likely compounding other factors.
Contact Lens Wear
A contact lens physically splits your tear film into two thinner layers, one in front of the lens and one behind it. This disrupts the normal spread of the oil layer, reduces tear film stability, and increases evaporation. The result is less lubrication and more friction between the lens and the eye’s surface.
Lens age matters. Studies comparing disposable lenses to conventional ones found that symptoms of discomfort were lower in the disposable group, and daily disposables performed better than two-week replacement lenses. Comfort typically holds steady for the first few hours of wear, then declines noticeably after about four hours. Newer water gradient lens designs, which maintain about 80% water content at the surface, have shown less disruption to the tear film after six hours of wear compared to standard silicone hydrogel lenses.
Eye Surgery
LASIK and other refractive eye surgeries are a well-documented cause of dry eyes, because the procedure cuts through corneal nerves that signal your brain to produce tears. Immediately after LASIK, 95% of patients report some dry eye symptoms. At one month, that number is still around 60%.
Nerve fibers begin regenerating about three months after surgery, starting at the edges of the cornea and slowly extending toward the center. Some connections between nerve segments become visible by six months. Most clinical signs of dry eye and corneal sensation return to pre-surgery levels within six months to a year, though nerve structure can remain subtly altered beyond that point. Surgeons typically manage post-LASIK dryness with lubricating drops during this recovery window.
Nutritional Deficiencies
Vitamin A plays a critical role in maintaining the mucus-producing goblet cells on the eye’s surface. When vitamin A levels drop too low, these cells stop functioning normally, leading to loss of both tears and the mucus layer that helps tears adhere to the eye. In more advanced deficiency, the conjunctiva (the clear tissue covering the white of your eye) undergoes a transformation where its cells start behaving more like skin than a moist membrane, producing a dry, white keratin deposit. While severe vitamin A deficiency is uncommon in developed countries, it remains a significant cause of dry eye and vision problems globally, particularly in regions where dietary intake of vitamin A-rich foods is limited.
Aging
Tear production naturally declines with age. The lacrimal glands produce less of the watery component, and the meibomian glands progressively lose function, reducing the oil layer’s effectiveness. These changes are gradual and cumulative, which is why dry eye prevalence rises steadily in people over 50. General population estimates range from 5% to over 30% depending on the study and diagnostic criteria, with the highest rates in older adults. Aging alone rarely explains severe symptoms, but it lowers your baseline tear quality enough that other triggers, like screen use, medications, or a dry environment, can push you over the threshold into noticeable discomfort.