Dry eyes happen when your tears evaporate too quickly, when your eyes don’t produce enough tears, or when the tears you make are missing key ingredients. The most common culprit, responsible for roughly 70% of dry eye cases, is a problem with the tiny oil glands along your eyelid margins. But the full list of causes is surprisingly long, spanning everything from the medications in your cabinet to the humidity in your home.
How Your Tear Film Works
Your tears aren’t just water. They’re a three-layer film: an outer oily layer that prevents evaporation, a middle watery layer that provides moisture and nutrients, and an inner mucus layer that helps tears stick evenly across the eye’s surface. A breakdown in any one of these layers creates a different flavor of dry eye, which is why the condition can feel so different from person to person. Someone with an oily layer problem might notice their eyes feel fine in the morning but worsen throughout the day, while someone who simply doesn’t produce enough of the watery layer may wake up with gritty, irritated eyes.
Oil Gland Problems
The oil-producing glands lining your upper and lower eyelids, called meibomian glands, are the single biggest source of dry eye trouble. When these glands become clogged, inflamed, or start producing poor-quality oil, your tears lose their protective outer seal and evaporate off the eye’s surface far too quickly. Studies pooling data from multiple dry eye populations estimate that about 70% of people with dry eye have some degree of meibomian gland dysfunction.
This type of dry eye tends to worsen with age because the glands gradually shrink and produce less oil over time. Chronic inflammation along the eyelids (blepharitis) often goes hand in hand with it, creating a cycle of irritation that feeds on itself.
Screens and Blinking
Your blink rate drops dramatically when you’re focused on a screen. Under relaxed conditions, most people blink around 18 to 22 times per minute. During computer use, that number can plummet to as few as 3 to 7 blinks per minute. Each blink re-spreads the tear film across your eye, so when you blink less, the film breaks apart and exposes patches of the cornea to air. On top of that, many of the blinks you do make during screen time are incomplete, meaning your upper lid doesn’t fully close. This leaves the lower portion of your cornea chronically under-lubricated.
If your dry eye symptoms are worst at the end of a workday or after a long stretch of reading, reduced blinking is a likely contributor.
Medications That Dry Your Eyes
A wide range of common medications list dry eye as a side effect, and in older adults, systemic medications may account for as many as 62% of dry eye cases. The most well-known offenders include antihistamines (both over-the-counter allergy pills and sleep aids), antidepressants, blood pressure medications, diuretics, anti-anxiety drugs, and pain relievers like ibuprofen and aspirin.
Some of these drugs reduce tear production directly by affecting the glands that make tears. Others work through a more unusual mechanism: certain compounds are actually secreted into the tear film itself, where they can form tiny crystals that irritate the eye’s surface. Even eye drops prescribed for other conditions can backfire. Glaucoma drops, for instance, cause burning and dry eye symptoms in up to 47% of the people who use them, often because of preservatives in the formulation.
If your dry eye started or worsened around the same time you began a new medication, that connection is worth exploring with your prescriber.
Hormonal Changes
Dry eye is significantly more common in women, and hormonal shifts are a major reason why. As estrogen, progesterone, and testosterone levels decline during perimenopause and menopause, the meibomian glands produce less oil and lower-quality oil. The result is a tear film that becomes unstable and evaporates too quickly. This is the same evaporative mechanism behind oil gland dysfunction, but hormone-driven changes can accelerate it earlier than aging alone would.
Hormonal contraceptives and hormone replacement therapy can also influence tear production, though the effects vary from person to person.
Autoimmune and Inflammatory Conditions
Several systemic diseases directly attack the glands responsible for keeping your eyes moist. Sjögren’s syndrome is the most prominent example. It’s an autoimmune condition in which the immune system targets moisture-producing glands throughout the body, causing severe dry eyes and dry mouth. Sjögren’s frequently occurs alongside other autoimmune diseases, particularly rheumatoid arthritis and lupus, a pattern known as secondary Sjögren’s.
Other inflammatory conditions linked to dry eye include thyroid eye disease, rosacea (which often inflames the eyelids), and diabetes, which can damage the nerves that signal tear production.
Your Environment
The air around you has a direct impact on how quickly your tears evaporate. Dry climates, forced-air heating and cooling, airplane cabins, and ceiling fans all strip moisture from the eye’s surface. Indoor humidity levels of about 45% or higher are generally the most comfortable for your eyes. Many heated or air-conditioned rooms fall well below that threshold, especially in winter.
Dusty environments, cigarette smoke, and even how your computer monitor is positioned play a role. A screen placed above eye level forces your eyes to open wider, exposing more of the corneal surface to air and accelerating evaporation. Positioning your screen slightly below eye level lets your lids cover more of the eye naturally.
Nutritional Deficiencies
Vitamin A is essential for your eyes to produce the moisture that keeps the cornea lubricated. When vitamin A levels drop low enough, a condition called xerophthalmia develops, progressing through stages of increasing dryness. First the white of the eye dries out, then the cornea itself becomes dry, and if untreated, permanent damage and even blindness can follow. While severe vitamin A deficiency is uncommon in developed countries, mild insufficiency can still contribute to a chronically unstable tear film.
Omega-3 fatty acids also support the oily layer of the tear film. People who eat very little fish, flaxseed, or other omega-3 sources may notice their tears evaporate more readily.
Eye Surgery
Refractive surgeries like LASIK and PRK temporarily disrupt the corneal nerves that trigger tear production, and dry eye is the most common complaint afterward. In a large study tracked by the American Academy of Ophthalmology, about 6% of eyes developed clinically significant dry eye between one and six months after surgery. LASIK carried a higher risk than PRK (52% vs. 39% in a direct comparison), because the LASIK flap cuts through more corneal nerves.
For most people, post-surgical dry eye is temporary and improves over several months as nerves regenerate. A smaller percentage develop symptoms that persist beyond a year, particularly if they had borderline dry eye before the procedure.
Contact Lens Wear
Contact lenses sit directly on the tear film and can disrupt all three of its layers. They absorb moisture from the watery layer, interfere with the even spread of the oily layer, and create friction against the mucus layer. Over time, long-term lens wear can reduce corneal sensitivity, meaning your eyes become less effective at signaling the need for fresh tears. Soft lenses that aren’t replaced on schedule or that have a low water content tend to cause the most issues.
Aging
Tear production naturally declines with age. Both the volume of tears and their composition change: the watery component decreases, the oil glands produce less effectively, and the mucus-producing cells on the eye’s surface become fewer. This is why dry eye prevalence climbs steeply after age 50 and is one of the most common eye complaints among older adults. Aging often acts as a foundation that other factors, like medications, screen time, or hormonal changes, build on.