Dry eye syndrome is a chronic condition where your tears can’t adequately lubricate your eyes, leading to stinging, burning, and blurred vision. It affects roughly 35% of adults worldwide, making it one of the most common eye conditions. The formal medical definition describes it as a multifactorial disease involving tear film instability, increased salt concentration in the tears, and inflammation of the eye’s surface.
How Your Tear Film Works
Your tears aren’t just saltwater. They form a three-layered film that coats the front of your eye every time you blink. The outermost layer is an oily film produced by tiny glands along your eyelid margins. This lipid layer smooths the optical surface of your cornea and, critically, slows evaporation. Beneath it sits a watery layer produced by the lacrimal glands, which delivers oxygen, nutrients, and infection-fighting proteins. The innermost layer is a mucus coating anchored to the surface cells of the eye itself. This mucus layer makes the eye’s surface wettable so tears can spread evenly rather than bead up.
When any one of these layers is compromised, the entire film becomes unstable. It breaks apart between blinks, leaving patches of exposed cornea. That exposure triggers the irritation, redness, and fluctuating vision people associate with dry eye.
Two Main Types of Dry Eye
Dry eye falls into two broad categories, and many people have a combination of both.
Aqueous-deficient dry eye happens when your lacrimal glands don’t produce enough of the watery component of tears. This can result from autoimmune conditions like Sjögren’s syndrome, aging, or damage to the glands themselves.
Evaporative dry eye is the more common form. Your glands produce a normal volume of tears, but the tears evaporate too quickly. The usual culprit is dysfunction in the meibomian glands, the oil-producing glands in your eyelids. When these glands become clogged or inflamed, the protective oily layer thins out and tears evaporate off the eye’s surface faster than they should.
Common Causes and Risk Factors
Medications are a major and often overlooked trigger. In older adults, an estimated 62% of dry eye cases can be traced to systemic medications, including antihistamines, diuretics, antidepressants, blood pressure medications, anti-anxiety drugs, and over-the-counter pain relievers like NSAIDs. If your dry eye symptoms started around the same time as a new prescription, that connection is worth exploring with your doctor.
Screen time plays a significant role for younger adults. You normally blink about 15 to 20 times per minute, but during focused screen work your blink rate can drop to roughly 10 blinks per minute. Each blink refreshes the tear film, so fewer blinks mean longer stretches of evaporation between refreshes. This is a key reason dry eye prevalence among people under 40 is now around 35%, nearly matching older age groups.
Other common contributors include low-humidity environments (air conditioning, airplane cabins, forced-air heating), contact lens wear, hormonal changes during menopause, and prior eye surgeries like LASIK.
What Dry Eye Feels Like
The symptoms can seem contradictory. Your eyes may feel gritty, sandy, or burning, yet also water excessively. That reflex tearing happens because the irritated surface triggers an emergency flood of low-quality tears that don’t stick around long enough to help. Other common symptoms include redness, sensitivity to light, a feeling of something stuck in your eye, and blurred vision that temporarily clears when you blink.
Symptoms tend to worsen later in the day, after prolonged reading or screen work, and in dry or windy environments. Many people notice a seasonal pattern, with winter heating and low humidity making things worse.
How It’s Diagnosed
Eye doctors use a few straightforward tests. The Schirmer test places a small strip of filter paper inside your lower eyelid to measure tear production over five minutes. Less than 10 millimeters of wetting generally suggests aqueous deficiency. A tear breakup time test uses a fluorescent dye to watch how quickly your tear film breaks apart after a blink. A stable film lasts 8 to 10 seconds or longer. In mild to moderate aqueous-deficient dry eye, the film can break apart in just 2 to 3 seconds.
Your doctor may also examine the meibomian glands for blockages and look at the corneal surface under magnification for signs of damage.
Treatment: Starting Simple
Artificial tears are the first-line treatment for most people. Standard bottled drops contain preservatives that prevent bacterial growth after opening, but those preservatives can irritate sensitive eyes with repeated use. If you’re reaching for drops more than four times a day, or if your dry eye is moderate to severe, preservative-free single-use vials are the better choice.
Environmental adjustments make a real difference alongside drops. Using a humidifier, positioning yourself away from direct air vents, and taking deliberate blink breaks during screen work all reduce tear evaporation. For people whose dry eye is linked to meibomian gland dysfunction, warm compresses applied to the eyelids for 5 to 10 minutes can soften clogged oil and improve the quality of the lipid layer.
Prescription Options
When over-the-counter drops aren’t enough, prescription anti-inflammatory eye drops target the underlying cycle of inflammation that perpetuates dry eye. The most widely used contain cyclosporine, an ingredient that calms immune activity on the eye’s surface and helps restore natural tear production. These drops come in several concentrations and formulations, including preservative-free versions. A different prescription drop uses lifitegrast, which works through a separate anti-inflammatory pathway. Both types typically take several weeks to reach full effect, so they’re used alongside artificial tears in the meantime.
In-Office Procedures
For people who don’t get enough relief from drops alone, punctal plugs are a common next step. These are tiny, painless inserts placed into the tear drainage channels at the inner corners of your eyelids. By blocking the outflow, they keep your natural tears on the eye’s surface longer. The procedure takes just a few minutes, and studies consistently show effectiveness rates above 70%. Some plugs are temporary and dissolve over weeks, while others are designed to stay in place long-term. They can be removed if needed.
For evaporative dry eye driven by meibomian gland dysfunction, in-office thermal treatments use controlled heat and pressure to clear blocked glands and restore healthy oil flow. These sessions typically last 10 to 15 minutes and may need to be repeated periodically.
What Happens Without Treatment
Mild dry eye is uncomfortable but manageable. Left untreated as it progresses, the consequences become more serious. A chronically dry corneal surface is vulnerable to small abrasions that can develop into corneal ulcers, which are open wounds on the front of the eye. Without an adequate tear film acting as a barrier, the risk of infectious keratitis rises. This type of corneal infection causes pain and is considered the fifth leading cause of blindness worldwide.
Over time, chronic inflammation and repeated surface damage can cause corneal scarring, known as corneal fibrosis. Scar tissue on the cornea blocks light from reaching the retina clearly, and the only way to restore vision lost to significant scarring is a corneal transplant. These complications are uncommon with proper management, but they underscore why persistent dry eye symptoms are worth addressing rather than enduring.