Chronic dry eye happens when your tears evaporate too quickly, your eyes don’t produce enough tears, or the tears you make are poor quality. It affects roughly 35% of adults globally, with higher rates in women (39%) compared to men (31%), and it becomes more common after age 40. The causes range from gland problems in your eyelids to hormones, medications, and everyday habits like screen time.
How Your Tear Film Works
Your eyes are coated in a thin layer of fluid that does more than keep things moist. The tear film protects the surface of your eye from debris and infection, and it’s also essential for clear vision. This film is made up of three components: an oily outer layer that slows evaporation, a watery middle layer that provides moisture and nutrients, and a mucus layer closest to the eye that helps tears spread evenly across the surface.
When any of these layers breaks down, the tear film becomes unstable. The watery layer evaporates faster, the surface of the eye dries out, and inflammation sets in. A healthy tear film stays intact for at least 10 seconds between blinks. In people with dry eye disease, it can break apart in under 5 seconds, leaving patches of the cornea exposed and irritated.
Blocked Oil Glands in the Eyelids
The single most common cause of chronic dry eye is a condition called meibomian gland dysfunction, or MGD. Your eyelids contain dozens of tiny oil-producing glands that line the rim where your lashes grow. These glands secrete a thin oil that forms the outermost layer of your tear film, slowing evaporation. When the glands become clogged, that oil either stops flowing or thickens into a waxy paste that can’t do its job.
The blockage happens when the lining of the gland ducts thickens and hardens over time. Aging is the primary driver: an estimated 70% of Americans over 60 have some degree of MGD. Reduced levels of androgens (hormones that help regulate oil production) also play a role, which partly explains why MGD worsens with age and disproportionately affects women after menopause. Without that protective oil layer, tears evaporate off the eye surface far too quickly, even if tear production itself is normal.
Hormonal Changes After Menopause
Dry eye is significantly more common in women, and hormonal shifts are a major reason. After menopause, levels of both estrogen and androgens (like testosterone) drop. Research shows that androgen levels are the more critical factor for tear production. In animal studies, the loss of androgens caused tear output to drop by roughly 50% within three months, and the tear film broke apart much faster.
Interestingly, estrogen itself may actually worsen dry eye rather than help it. When researchers gave estrogen supplements to animals whose ovaries had been removed, tear production dropped even further and the tear film became less stable. Testosterone had the opposite effect, improving both tear volume and tear film stability. This is because estrogen increases the activity of enzymes that break down tissue in the tear glands, while testosterone suppresses those same enzymes. It’s one reason why hormone replacement therapy focused on estrogen doesn’t reliably improve dry eye symptoms, and why researchers are exploring androgen-based treatments instead.
Medications That Reduce Tear Production
An estimated 62% of dry eye cases in older adults can be traced to systemic medications. The list of culprits is long: antihistamines, antidepressants, blood pressure medications, diuretics, anti-anxiety drugs, pain relievers, and many others. Most of these drugs share a common mechanism. They block a type of receptor on cells that’s involved in secreting tears, mucus, and oils. The drug may be targeting that receptor for a completely different purpose (reducing allergy symptoms, for example), but the tear glands get caught in the crossfire.
Some medications cause dry eye through a different route entirely. Drugs like aspirin, ibuprofen, and certain heart and arthritis medications are actually secreted into the tear film, where they can form tiny crystals that irritate the eye surface. Glaucoma eye drops are another common offender, causing burning and dryness in up to 47% of patients. The issue there is usually a preservative in the drops that’s directly toxic to cells on the eye surface and triggers chronic inflammation.
Screen Time and Reduced Blinking
Every time you blink, you spread a fresh coat of tears across your eyes. At rest, most people blink about 15 to 16 times per minute. When reading on a tablet or computer, that rate drops to around 6 blinks per minute, a reduction of more than 60%. This isn’t unique to screens. Hard-copy reading causes a similar drop. But because many people spend 8 or more hours a day focused on digital devices, the cumulative effect on the tear film is substantial.
Fewer blinks means longer gaps between each fresh coating of tears, giving the existing film more time to thin and break apart. Over months and years, this pattern can shift from occasional discomfort to chronic dry eye with persistent inflammation. The problem compounds in office environments, where air conditioning and heating systems lower indoor humidity. Tear evaporation has a direct inverse relationship with humidity: it climbs steadily as humidity drops below 70%, and dry eye patients lose moisture from the eye surface even faster than people with healthy tear films in the same low-humidity conditions.
Autoimmune Diseases
Certain autoimmune conditions attack the glands responsible for producing tears. Sjögren’s syndrome is the most well-known example. In this disease, the immune system targets moisture-producing glands throughout the body, particularly the tear glands and salivary glands. Over 81% of people with Sjögren’s syndrome have dry eye disease, making it nearly universal in this population.
Other autoimmune conditions linked to chronic dry eye include rheumatoid arthritis, lupus, and thyroid disease. In these cases, the inflammation isn’t always directed at the tear glands themselves, but the systemic inflammatory response disrupts tear production and quality. If your dry eyes appeared alongside other symptoms like chronic joint pain, extreme fatigue, or a persistently dry mouth, an autoimmune condition could be the underlying driver.
Eye Surgery
LASIK and other refractive eye surgeries are a well-recognized cause of dry eye. During LASIK, the surgeon cuts a flap in the cornea, severing tiny nerves that signal your brain to produce tears. Without those signals, the reflex that keeps your eyes moist is temporarily disrupted. Estimates of how many LASIK patients experience dry eye afterward range widely, from about 4% to as high as 60 to 70%, depending on how dryness is measured and how long after surgery patients are evaluated.
For most people, the dryness resolves within 3 to 6 months as the corneal nerves regrow. But for a subset of patients, symptoms persist for a year or longer. People who already had borderline dry eye before surgery, or who have risk factors like autoimmune disease, are more likely to develop lasting symptoms. Cataract surgery can also trigger or worsen dry eye through a similar nerve-disruption mechanism, though it tends to be milder.
Aging and Inflammation
Dry eye becomes progressively more common with age, independent of any single cause. Tear production naturally declines over time. The meibomian glands slowly atrophy, producing less oil. The surface of the eye becomes more prone to inflammation, and that inflammation further damages the glands and cells responsible for healthy tears, creating a self-reinforcing cycle.
This is why chronic dry eye is rarely caused by just one factor. A 55-year-old woman taking an antihistamine and working at a computer in a climate-controlled office may have four or five contributing causes layered on top of each other: age-related gland changes, hormonal shifts, medication effects, reduced blinking, and low humidity. Identifying which factors are most significant is what allows targeted treatment rather than simply adding artificial tears indefinitely.