Dry eye happens when your tears can’t keep the surface of your eyes properly lubricated, either because you’re not producing enough tears or because the tears you do produce evaporate too quickly. It affects roughly one in five adults in North America, and globally the number is even higher, closer to one in three. The cause is rarely a single factor. Most people have some combination of environment, screen habits, medications, hormones, or an underlying health condition working against them.
How Your Tear Film Works
Your tears aren’t just salt water. They have three distinct layers that work together: an outer oily layer that slows evaporation, a middle watery layer that provides moisture and nutrients, and an inner mucus layer that helps tears spread evenly across the eye’s surface. When any one of these layers is off, the whole system breaks down. Dry eye falls into two broad categories based on which part is failing.
The more common type is evaporative dry eye, where tiny oil glands along your eyelid margins (called meibomian glands) aren’t producing enough oil or are producing poor-quality oil. Without that protective oily layer, your tears evaporate faster than they should. This type tends to get worse as the day goes on, especially after hours of screen time or exposure to dry air.
The second type is aqueous deficient dry eye, where the glands responsible for the watery portion of your tears aren’t producing enough fluid. This type is more closely linked to autoimmune conditions and tends to be worst first thing in the morning. Many people have elements of both.
Screens and Blinking
You normally blink about 15 times per minute. When you’re staring at a computer, phone, or tablet, that drops to 5 to 7 times per minute. Since blinking is what spreads fresh tears across the surface of your eye, cutting your blink rate by more than half means your tear film is breaking apart and drying out between blinks. If your eyes feel fine in the morning but gritty and irritated by late afternoon, screen use is likely a major contributor.
The fix sounds simple but takes effort: consciously blink more often, and follow the 20-20-20 rule (every 20 minutes, look at something 20 feet away for 20 seconds). Positioning your screen slightly below eye level also helps, because it reduces the amount of exposed eye surface and slows evaporation.
Medications That Dry Your Eyes
A surprising number of common medications interfere with tear production. If your dry eye started or worsened around the time you began a new prescription, the drug itself may be the problem.
- Antihistamines and decongestants: Allergy medications reduce tear production as a side effect. Nasal decongestants do the same.
- Antidepressants: Tricyclic antidepressants are well known for drying out the eyes, but SSRIs can also cause it.
- Blood pressure medications: Beta-blockers reduce a key protein in your tears, lowering both tear volume and quality. Diuretics change your body’s fluid balance, which alters tear composition too.
- Hormonal birth control and hormone replacement therapy: Women taking estrogen alone are significantly more likely to develop dry eye than those taking estrogen combined with progesterone.
- Isotretinoin for acne: This drug works by reducing oil production throughout your body, including the oil glands in your eyelids. That strips the protective lipid layer from your tears.
- Over-the-counter pain relievers: Even ibuprofen and other NSAIDs can occasionally cause dry eye, though this is less common.
Hormonal Changes and Aging
Aging is one of the strongest risk factors for dry eye, and hormones are a big part of the reason. Women are disproportionately affected, particularly during and after menopause. The drop in estrogen, progesterone, and testosterone that begins in perimenopause directly impacts the meibomian glands, resulting in lower oil volume and poorer oil quality in tears. This means tears evaporate faster even if the watery component is still adequate.
This hormonal connection explains why dry eye often appears seemingly out of nowhere for women in their 40s and 50s. Men experience a more gradual decline in tear production with age, but the effect is less dramatic because their androgen levels drop more slowly.
Environmental Triggers
Your surroundings play a constant role. Low humidity is a major culprit, and it’s more common indoors than most people realize. Running a heater in winter or air conditioning in summer both strip moisture from the air, which accelerates tear evaporation. If you’ve noticed your eyes are worse in certain seasons, this is likely why. Even a humidifier can struggle to keep up when extreme outdoor temperatures force your HVAC system to work harder.
Wind is another trigger, including sources you might not think of. Sleeping with a ceiling fan, a bedside fan pointed near your face, or a CPAP mask that leaks air toward your eyes can all cause significant overnight drying. Smoke, allergens, and high altitudes round out the list of environmental factors that destabilize the tear film.
Underlying Health Conditions
Persistent, severe dry eye that doesn’t respond to typical remedies can signal an underlying autoimmune or systemic condition. Sjögren’s syndrome is the most well-known culprit. It causes the immune system to attack moisture-producing glands throughout the body, including the lacrimal glands that make the watery layer of your tears. Over time, this can significantly damage or destroy those glands.
Other conditions linked to dry eye include rheumatoid arthritis, lupus, scleroderma, thyroid disorders, and sarcoidosis. Vitamin A deficiency, though rare in developed countries, can also impair tear production. Allergic eye disease is another common overlap: the inflammation from chronic eye allergies disrupts the tear film independently of any allergy medication you might be taking.
If your dry eye is accompanied by a persistently dry mouth, joint pain, fatigue, or skin changes, those symptoms together may point toward one of these systemic causes.
What Actually Helps
Treatment depends entirely on which type of dry eye you have, and getting this distinction right matters. Treatments designed for aqueous deficiency can actually make evaporative dry eye worse. For example, punctal plugs (tiny devices inserted into tear drainage ducts to keep tears on the eye longer) work well for people who don’t produce enough tears, but they can worsen symptoms in people with meibomian gland dysfunction by trapping poor-quality, inflamed tears on the eye surface.
For evaporative dry eye, the focus is on improving oil gland function. Warm compresses held against your closed eyelids for several minutes help soften and release blocked oils. Lid hygiene with gentle cleansers keeps those glands clear. Artificial tears labeled “lipid-based” or “for evaporative dry eye” add back the missing oil layer rather than just adding more water.
For aqueous deficient dry eye, preservative-free artificial tears are the first step. Prescription anti-inflammatory drops can help when the lacrimal glands are inflamed, particularly in people with autoimmune conditions. These drops work best for that specific type and are less effective for evaporative causes.
Across both types, reducing screen time (or at least taking frequent breaks), using a humidifier in dry rooms, wearing wraparound sunglasses outdoors on windy days, and reviewing your medication list for known offenders are practical changes that often make a noticeable difference.