Dry eyes happen when your tears can’t keep your eye surface properly lubricated, either because you’re not producing enough tears or because your tears evaporate too quickly. With a global prevalence around 35%, it’s one of the most common eye complaints, and the causes range from everyday habits like screen time to underlying medical conditions and hormonal shifts.
How Your Tear Film Works
Your tears aren’t just saltwater. They form a complex three-layer film across the surface of your eye, and a problem in any layer can trigger dryness. The innermost layer is made of mucin, a sticky substance produced by cells in the membrane lining your eyelids. Mucin anchors the watery layer to the surface of your eye, which would otherwise repel moisture. The middle layer is the thickest and contains water, proteins, salts, and dissolved oxygen that nourish and protect the eye’s surface. The outermost layer is an ultra-thin coat of oil produced by tiny glands along your eyelid margins called meibomian glands. This oily layer is surprisingly complex, containing over 600 unique lipids, and its primary job is to slow evaporation so your tears stick around long enough to do their work.
When something disrupts any of these layers, the whole system breaks down. The watery layer evaporates too fast, debris isn’t flushed away properly, and the eye surface becomes inflamed and irritated.
Meibomian Gland Dysfunction
The single most common driver of dry eye is a problem with the oil-producing glands in your eyelids. When these meibomian glands become blocked or produce poor-quality oil, tears evaporate faster than they should. This triggers a chain reaction: the remaining tears become too concentrated (hyperosmolar), which irritates the eye surface and sparks inflammation, which damages the surface further, which makes the dryness worse.
Population studies have found that roughly 30% of people have some degree of meibomian gland dysfunction, many without realizing it. It tends to worsen with age and is more common in people who wear eye makeup, have skin conditions like rosacea, or have chronic eyelid inflammation. If your dry eyes feel worse in the morning or your eyelids feel crusty or sticky, gland dysfunction is a likely contributor.
Screen Time and Reduced Blinking
Your blink rate drops dramatically when you focus on a screen. In a relaxed state, most people blink about 22 times per minute. While reading a book, that falls to around 10. While staring at a screen, it drops to roughly 7 blinks per minute. One study found that blink rates during computer use fell to just 42% of the resting rate. Every blink spreads a fresh layer of tears across your eye, so fewer blinks means your tear film has more time to break apart and evaporate between refreshes.
This is a major reason dry eye prevalence spiked during the COVID-19 pandemic, when screen time surged. Studies from that period found dry eye rates as high as 44.5% among the populations studied. The effect compounds over time: hours of reduced blinking day after day can lead to chronic inflammation of the eye surface that persists even when you step away from the screen.
Environmental Triggers
Your surroundings directly control how fast tears evaporate. Three factors matter most: humidity, air movement, and temperature. Air conditioning and indoor heating both reduce ambient humidity, pulling moisture from your tear film faster. Direct airflow over your face, whether from a car vent, ceiling fan, or airplane cabin, accelerates the process even further. Measurements in commercial aircraft cabins have recorded humidity plunging from a normal 47% down to 11% shortly after takeoff, which explains why so many people experience dry, irritated eyes during flights.
Wind, high altitude, and dry climates all have the same basic effect. If you notice your eyes feel fine at home but burn and itch at the office, the culprit is often an HVAC vent positioned near your workspace.
Medications That Dry Your Eyes
A surprisingly long list of common medications can reduce tear production or change tear composition as a side effect. The most frequent offenders include:
- Antihistamines (allergy medications), which block the same chemical signals that help stimulate tear production
- Antidepressants, particularly older tricyclic types and some SSRIs
- Blood pressure medications, including beta blockers and certain other classes of antihypertensives
- Anti-inflammatory drugs, both corticosteroids and common over-the-counter pain relievers
- Glaucoma eye drops, especially those containing preservatives, which can damage the eye surface with long-term use
If you started a new medication and noticed dryness within weeks, the timing is worth mentioning to your prescriber. In many cases, switching to an alternative in the same drug class can resolve the problem.
Hormonal Changes
Dry eye affects women significantly more often than men, with prevalence rates of about 39% in women compared to 31% in men. A key reason is the influence of sex hormones on tear production. Both estrogen and androgens affect every component of the tear film, including the watery layer, the oil layer, and the mucin layer.
The relationship is counterintuitive. Androgens (often thought of as “male” hormones, though women produce them too) actually stimulate the meibomian glands to produce the oily layer that prevents evaporation. As androgen levels decline with age, oil production drops and tears evaporate faster. Estrogen, on the other hand, appears to decrease lipid production from those same glands. This means the hormonal shifts of perimenopause and menopause, when androgen levels fall and estrogen levels fluctuate, create a perfect storm for dry eye. Hormone replacement therapy that raises estrogen without balancing androgens can sometimes make dryness worse rather than better.
Pregnancy and oral contraceptive use can also trigger dry eye episodes for similar reasons.
Autoimmune Conditions
Sjögren’s syndrome is the autoimmune disease most closely linked to dry eye. In Sjögren’s, the immune system attacks the glands that produce tears and saliva, leading to persistent, often severe dryness of the eyes and mouth. It can occur on its own (primary Sjögren’s) or alongside another autoimmune condition (secondary Sjögren’s). The most commonly associated conditions are rheumatoid arthritis and lupus, though scleroderma, Raynaud’s disease, and certain liver conditions have also been linked.
If your dry eyes are accompanied by a persistently dry mouth, joint pain, or fatigue, an autoimmune condition may be the underlying cause. Sjögren’s-related dry eye tends to be more severe and harder to manage with over-the-counter drops alone because the tear glands themselves are being gradually damaged.
Aging and Tear Gland Decline
Dry eye prevalence rises with age, affecting about 37% of people over 40. The lacrimal glands that produce the watery component of tears gradually become less active over the decades. The meibomian glands also shrink and produce less oil. At the same time, the mucin-producing goblet cells in the eyelid lining decrease in number, weakening the foundation layer that holds tears to the eye surface. These changes are slow and cumulative, which is why many people first notice dry eye symptoms in their 40s or 50s and find them gradually worsening.
Eye Surgery
LASIK is the most well-known surgical cause of dry eye. During the procedure, corneal nerves that trigger the blink reflex and stimulate tear production are severed. Dry eye is the most common post-LASIK complication: virtually all patients experience some degree of dryness in the weeks following surgery, and studies report that 20% to over 50% of patients develop clinically significant dry eye disease afterward. For most people, symptoms improve over 6 to 12 months as nerves regenerate, but a subset experience chronic dryness that persists for years.
Cataract surgery can cause similar, though typically milder, disruption to the eye surface. If you’re considering any eye surgery, existing dry eye should be treated beforehand, as it tends to worsen outcomes.
Contact Lens Wear
Contact lenses sit directly in the tear film and disrupt its structure. The lens splits the tear film into a thin layer above and below it, accelerating evaporation from the front surface. Soft lenses in particular absorb water from surrounding tears to maintain their shape. Low-humidity environments like air-conditioned offices or airplane cabins compound the problem, pulling moisture from the lens surface faster than tears can replenish it. Long-term contact lens wear can also reduce corneal nerve sensitivity over time, diminishing the signals that tell your brain to produce more tears.