Dry eye is a condition where your eyes don’t produce enough tears or the tears evaporate too quickly, leaving the surface of your eye exposed and irritated. It affects hundreds of millions of people worldwide and ranges from mild, occasional discomfort to a chronic disease that can damage your cornea over time. The hallmark symptoms are stinging, burning, grittiness, and, paradoxically, watery eyes as your body tries to compensate for the dryness.
How Your Tear Film Works
Your tears aren’t just saltwater. They form a thin, three-layered film that coats the front of your eye every time you blink. Each layer has a specific job, and problems in any one of them can trigger dry eye.
The innermost layer is made of mucins, sticky proteins produced mainly by cells in the clear membrane covering your eye. This layer anchors the watery tears to the eye’s surface, which is naturally water-repellent. Without it, tears would bead up and slide off instead of spreading evenly. The middle layer is the thickest and does the heavy lifting: lubricating, delivering oxygen and nutrients, and flushing away debris and toxins. It’s produced by your lacrimal (tear) glands, located above each eye. The outermost layer is a thin film of oil secreted by tiny glands along your eyelid margins called meibomian glands. This oil slows evaporation so the watery layer stays in place between blinks.
When any of these layers is insufficient, the tear film breaks apart too quickly. The exposed surface becomes saltier than it should be, triggering inflammation that damages the cells responsible for producing tears and mucus in the first place. This creates a self-reinforcing cycle: dryness causes inflammation, inflammation worsens dryness.
The Two Main Types
Dry eye generally falls into two categories, though many people have a combination of both.
Aqueous deficient dry eye means your lacrimal glands don’t produce enough of the watery middle layer. Research measuring tear flow rates found that people with this type produce roughly half the volume of tears that healthy eyes do. Even normal evaporation becomes a problem when there’s less fluid to begin with, because the remaining tears become concentrated and irritating.
Evaporative dry eye is the more common form and is usually caused by meibomian gland dysfunction, where the oil glands in your eyelids become clogged or produce poor-quality oil. Without that protective oil layer, tears evaporate off the eye’s surface too quickly. A tear film that breaks apart in under 8 seconds is generally considered unstable.
Common Causes and Risk Factors
Screen use is one of the biggest modern contributors. Your normal blink rate during relaxed activity is about 22 blinks per minute. Reading a book drops that to around 10. Staring at a screen drops it further, to about 7 blinks per minute. One study found that playing a computer game cut blink rates to roughly 42% of resting levels. Fewer blinks means the tear film has more time to break apart and evaporate between each refresh.
Several common medications reduce tear production or alter the tear film. Antihistamines, antidepressants, blood pressure medications, and corticosteroids are well-known culprits. Statins carry roughly double the odds of moderate to severe dry eye symptoms. Isotretinoin (used for acne) can disrupt the meibomian glands directly. Even eye drops themselves can contribute if they contain the preservative benzalkonium chloride (BAK), which damages the mucus-producing cells on the eye’s surface and triggers inflammation with repeated use.
Other major risk factors include aging (tear production naturally declines), hormonal changes (particularly after menopause), autoimmune conditions like Sjögren’s syndrome and rheumatoid arthritis, low indoor humidity, contact lens wear, and previous eye surgery including LASIK.
What Dry Eye Feels Like
The most common symptoms are a persistent scratchy or gritty sensation, as though something is in your eye. Burning, stinging, and redness are typical. Your eyes may feel heavy or fatigued, especially later in the day. Blurry vision that clears temporarily after blinking is another hallmark, since the uneven tear film distorts light entering the eye.
One of the most confusing symptoms is excessive tearing. When the eye’s surface dries out, it sends an emergency signal that triggers a flood of watery “reflex” tears. These tears lack the right balance of oil and mucus, so they don’t stick to the eye well and end up spilling down your cheeks without actually solving the dryness.
How It’s Diagnosed
An eye care provider can diagnose dry eye with a few straightforward tests. The Schirmer test involves placing a small strip of filter paper inside your lower eyelid for five minutes. Wetting more than 15 mm of the strip is considered normal. Less than 5 mm indicates a significant tear deficiency. The Dry Eye Workshop guidelines use 10 mm as the diagnostic cutoff.
A tear break-up time (TBUT) test uses a drop of dye on the eye’s surface while the provider watches through a microscope. They measure how many seconds it takes for the first dry spot to appear after a blink. A break-up time under 8 seconds suggests an unstable tear film. Providers also look at the health of your meibomian glands and the surface of your cornea for signs of damage.
First-Line Treatments
Artificial tears are the starting point for most people. If you use drops more than four times a day, preservative-free formulations are strongly preferred. The preservative BAK, found in many conventional eye drops, is toxic to the mucus-producing cells on the eye’s surface, reduces cell survival by 20 to 28%, cuts cell growth by nearly half, and increases inflammatory signaling. Over time, it can make dry eye worse rather than better. Preservative-free drops come in single-use vials or specialized multi-dose bottles.
For evaporative dry eye caused by clogged meibomian glands, warm compresses applied to the eyelids for 5 to 10 minutes help soften hardened oils. Gently massaging the lids afterward encourages the glands to release oil. Doing this daily can noticeably improve symptoms within a few weeks.
Environmental adjustments matter more than many people realize. Keeping indoor humidity at 45% or higher reduces tear evaporation. Positioning your screen slightly below eye level so your eyes are partially closed while working limits the exposed surface area. Taking regular breaks from screens (the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds) gives your blink rate a chance to recover.
Prescription and In-Office Options
When over-the-counter drops aren’t enough, prescription anti-inflammatory drops can break the cycle of inflammation driving the disease. These take several weeks to reach full effect, and some cause a temporary burning sensation at first.
For more stubborn meibomian gland dysfunction, in-office procedures can clear blocked glands more effectively than warm compresses alone. Intense pulsed light (IPL) therapy, originally developed for skin conditions, uses pulses of light applied to the skin around the eyes. The light energy heats and liquefies hardened oil in the glands, reduces inflammation by destroying abnormal blood vessels feeding the inflamed area, and can even eliminate tiny mites (Demodex) that colonize eyelash follicles and worsen gland blockages. Treatment typically requires multiple sessions spaced weeks apart.
Punctal plugs are another option. These are tiny devices inserted into the tear drainage channels in the corners of your eyelids, keeping your natural tears on the eye’s surface longer. They can be temporary (dissolvable) or semi-permanent, and insertion takes only a minute or two.
What Happens if Dry Eye Goes Untreated
Mild dry eye is uncomfortable but not dangerous. Chronic, severe dry eye is a different story. When the cornea is repeatedly left unprotected, it can develop persistent surface wounds that don’t heal normally. In studies of severe dry eye patients, 16% developed persistent corneal defects and 9% experienced corneal thinning or perforation, which is a medical emergency. Some patients also develop scarring of the conjunctiva (the clear membrane lining the eyelids) or damage to the stem cells that regenerate the corneal surface, both of which can permanently impair vision. These complications are most common in severe autoimmune-related dry eye, not the mild to moderate dry eye most people experience, but they underscore why persistent symptoms deserve proper evaluation and management.