Dry eye, explained properly

Dry eye isn’t simply a shortage of tears. It’s a breakdown of the thin film that protects the front of your eye, and the cause is usually not what people expect. Here’s what’s going on, how to tell which type you have, and which treatments the research supports.

By Symvana EditorialUpdated 9 min readHow we research
On this page
  1. What dry eye actually is
  2. Symptoms, including the confusing ones
  3. The two main types
  4. What causes it
  5. How eye doctors diagnose it
  6. Treatments that work, by type
  7. What doesn’t work as well as you’d think
  8. When to see an eye doctor
  9. Common questions

The short version

  • Dry eye is a problem with the tear film, the thin layer covering the front of the eye. Most often the oil layer is the weak point, not the amount of tears.
  • About 16 million US adults have a diagnosis. It’s more common in women and after 50.
  • Symptoms include grittiness, burning, blur that clears when you blink and, confusingly, watery eyes.
  • Treatment works best when it matches the cause: heat and lid care for blocked oil glands, moisture and anti-inflammatory drops for low tear production.
  • See an eye doctor if symptoms last more than a few weeks, and promptly for pain, a change in vision or a very red eye.

What dry eye actually is

Every time you blink, your eyelids spread a fresh tear film across the front of your eye. It’s only a few thousandths of a millimeter thick, yet it keeps the surface smooth enough to see clearly, feeds and protects the living cells underneath, and washes away dust and germs.

The film has three parts. A slippery mucin layer helps it cling to the eye. A watery middle layer does most of the hydrating. And a thin oil layer on top slows evaporation, the way a lid slows a pot of water from boiling dry.

Dry eye happens when that system loses its balance. The world’s leading expert panel on the condition, the Tear Film & Ocular Surface Society, updated its definition in 2025. It now describes dry eye as a symptomatic disease in which tear film instability, overly salty tears, inflammation, surface damage and nerve problems all feed into each other1 Association of Optometrists news, June 2025 (opens in a new tab). TFOS DEWS III updates definitions and diagnostic processes in dry eye.. Symptoms are now a required part of the diagnosis: if it doesn’t bother you, it isn’t dry eye disease.

That feedback loop is the key to understanding why dry eye tends to linger. An unstable film evaporates, the remaining tears get saltier, the saltier tears inflame the surface, and the inflamed surface holds the film even less well. Good treatment breaks the loop at more than one point.

Symptoms, including the confusing ones

Dry eye rarely feels just dry. The most common complaints are:

  • A gritty, sandy feeling, as if something is in your eye
  • Burning, stinging or aching
  • Eyes that feel tired and heavy, especially by evening
  • Blurry vision that clears for a moment when you blink
  • Discomfort that gets worse at screens, while reading, driving or in air-conditioned rooms
  • Contact lenses that become uncomfortable after a few hours
  • Sensitivity to light and wind

And then there’s the symptom that confuses almost everyone: watery eyes. When the eye surface dries out, its nerves trigger a burst of reflex tears. Those tears are mostly water, without the oil and mucin that make normal tears stick, so they spill over or evaporate quickly and the dryness comes straight back. Watery eyes can be a sign that you need better tears, not fewer.

The two main types

Eye doctors describe two broad types of dry eye. Many people have some of both.

Evaporative dry eye (the oil layer)

This is by far the most common. The meibomian glands, dozens of tiny oil glands along the edge of each eyelid, become blocked or produce thick, poor-quality oil. Without enough oil on top, the watery layer evaporates too fast. In a clinic-based study of people with dry eye, 86% showed signs of this meibomian gland dysfunction2 Lemp et al., Cornea, 2012 (opens in a new tab). Distribution of aqueous-deficient and evaporative dry eye in a clinic-based patient cohort..

Aqueous-deficient dry eye (the water layer)

Here, the tear glands don’t make enough of the watery part of tears. It’s more common with age, around menopause, with certain medications and with autoimmune conditions such as Sjögren’s, which attacks the tear and saliva glands.

EvaporativeAqueous-deficient
What failsOil layer, from the meibomian glandsWater layer, from the tear glands
Often worseLater in the day, on screens, in dry or moving airAll day, often with a dry mouth
CluesRed or crusty lid edges, rosacea, blur that clears on blinkingAge over 50, menopause, autoimmune disease, certain medications
Usually helped byHeat, lid hygiene, oil-based drops, IPL, thermal pulsationPreservative-free drops, humidity, anti-inflammatory drops, punctal plugs

Not sure which applies to you? The Dry Eye Profile weighs these clues and suggests the most likely pattern in about three minutes.

What causes it

Dry eye usually has more than one cause. The most common contributors are:

  • Age and hormones. In a national US survey, diagnosed dry eye rose from 2.7% of adults aged 18 to 34 to 18.6% of those 75 and older, and women were affected about twice as often as men3 Farrand et al., American Journal of Ophthalmology, 2017 (opens in a new tab). Prevalence of Diagnosed Dry Eye Disease in the United States Among Adults Aged 18 Years and Older..
  • Screens and concentration. People blink about 17 times a minute at rest but only around 4.5 times a minute while reading4 Bentivoglio et al., Movement Disorders, 1997 (opens in a new tab). Analysis of blink rate patterns in normal subjects.. On screens, a larger share of blinks don’t fully close5 Argilés et al., Investigative Ophthalmology & Visual Science, 2015 (opens in a new tab). Blink Rate and Incomplete Blinks in Six Different Controlled Hard-Copy and Electronic Reading Conditions., so the oil layer never gets properly spread.
  • Medications. Antihistamines, some antidepressants, certain blood pressure medicines, hormone treatments and the acne drug isotretinoin can all reduce tears or damage the oil glands6 Gomes et al., The Ocular Surface, 2017 (opens in a new tab). TFOS DEWS II iatrogenic report.. So can years of preserved eye drops, including some glaucoma drops.
  • Contact lenses and eye surgery. Lenses split the tear film and speed up evaporation. LASIK and other surgeries cut some corneal nerves, which dulls the signal to make tears. Post-surgery dryness often improves over months.
  • The eyelids themselves. Blepharitis, rosacea and an overgrowth of tiny Demodex mites can all inflame the lid margins and clog the oil glands. Read more about eyelid mites.
  • Air and sleep. Heating, air conditioning, fans, flights and wind all speed up evaporation. Eyes that don’t fully close during sleep, and air leaking from a CPAP mask, dry the surface all night.

How eye doctors diagnose it

There’s no single test for dry eye. Under the 2025 international criteria, a diagnosis needs symptoms, measured with a short questionnaire, plus at least one objective sign7 TFOS DEWS III, American Journal of Ophthalmology, 2025 (opens in a new tab). TFOS DEWS III: Diagnostic Methodology.. The signs doctors look for include:

  • Tear break-up time. How many seconds your tear film lasts after a blink before it starts to break apart. Under 10 seconds counts as unstable.
  • Tear osmolarity. How salty your tears are, measured from a tiny sample at the edge of the eye.
  • Surface staining. Harmless dyes that highlight damaged cells on the cornea and conjunctiva.

A dry eye specialist may also photograph your oil glands with infrared imaging, called meibography, measure tear volume, and check your lid margins for blockage or mites. Those extra tests don’t just confirm dry eye. They tell you which layer is failing, which decides the treatment.

Treatments that work, by type

Most eye doctors treat dry eye in steps, starting simple and adding more targeted treatments if symptoms continue. Here’s how the main options stack up. Our full evidence board grades 20 of them.

At home

Over the counter

  • Artificial tears Good evidence are the standard first treatment. A Cochrane review found they’re generally safe and can help, though many trials were small12 Pucker et al., Cochrane Database of Systematic Reviews, 2016 (opens in a new tab). Over the counter (OTC) artificial tear drops for dry eye syndrome.. Choose preservative-free if you use them more than about four times a day, and choose an oil-containing drop if your oil layer is the problem. Our drop guide sorts them by type.
  • Night ointments and gels protect the eye while you sleep, especially if you wake up with sore eyes.

Prescription

  • Anti-inflammatory drops Good evidence such as cyclosporine and lifitegrast target the inflammation that keeps dry eye going. They can take weeks to months to work.
  • Perfluorohexyloctane (Miebo) Good evidence, approved in 2023, sits on the tear film and slows evaporation13 BioSpace, May 2023 (opens in a new tab). FDA Approves Bausch + Lomb, Novaliq Dry Eye Disease Drug..
  • Tear-stimulating treatments Good evidence: acoltremon (Tryptyr), approved in 2025, works on the eye’s cold-sensing nerves to boost natural tear production14 Alcon press release, May 2025 (opens in a new tab). Alcon Announces FDA Approval of TRYPTYR (acoltremon ophthalmic solution) 0.003% for the Treatment of the Signs and Symptoms of Dry Eye Disease., and varenicline nasal spray (Tyrvaya) triggers tears through a nerve in the nose.
  • Lotilaner (Xdemvy) Strong evidence treats Demodex blepharitis. In a phase 3 trial it cleared lash debris in 56% of patients after six weeks, compared with 12.5% on placebo15 Saturn-2 phase 3 trial, Ophthalmology, 2023 (opens in a new tab). Lotilaner Ophthalmic Solution 0.25% for Demodex Blepharitis: Randomized, Vehicle-Controlled, Multicenter, Phase 3 Trial (Saturn-2)..
  • Short courses of steroid drops can calm flare-ups under an eye doctor’s supervision.

In a clinic

Not sure which type you have?

The free Dry Eye Profile sorts your symptoms into a likely type and gives you a plan in about three minutes.

Take the profile

What doesn’t work as well as you’d think

Omega-3 supplements. Mixed evidence For years, fish oil was a standard recommendation. Then the DREAM trial gave 535 people with dry eye either 3,000 mg of omega-3 a day or an olive oil placebo for a year. Both groups improved by about the same amount20 DREAM Study Research Group, New England Journal of Medicine, 2018 (opens in a new tab). n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease.. Some smaller trials have been more positive, so omega-3 isn’t useless, but it shouldn’t be your first move.

Drinking more water. Weak evidence Staying hydrated is good for you, but unless you’re genuinely dehydrated, extra water won’t fix a tear film problem.

Redness-relief drops. Not recommended They shrink blood vessels to whiten the eye. They don’t add moisture, and regular use can leave eyes redder when they wear off. Check labels with the Drop Decoder.

When to see an eye doctor

Book an appointment with an optometrist or ophthalmologist if dry eye symptoms last more than a few weeks despite home care, if they’re affecting your work, reading or driving, or if you need drops many times a day to get by. A dry eye specialist can run the tests that pin down your type and offer treatments nothing over the counter can match. Find a dry eye specialist.

See a doctor promptly if you have

Eye pain rather than discomfort, a sudden change in vision, strong light sensitivity, one eye much redder than the other, or thick discharge. These can signal infection or inflammation that needs treatment soon. If you wear contact lenses, take them out until you’ve been seen.

Common questions

Can dry eye be cured?

For some people, yes, especially when a clear cause such as a medication, a contact lens problem or blocked oil glands is fixed. For many others it’s a long-term condition that can be controlled very well with the right routine and treatments.

Can dry eye damage my vision?

Mild dry eye doesn’t cause permanent vision loss. Severe, untreated dry eye can damage the cornea over time and, rarely, lead to scarring or infection. That’s why persistent or worsening symptoms deserve an exam.

Why are my eyes watery if I have dry eye?

A dry eye surface triggers reflex tearing. Those reflex tears are thin and watery, without the oil that keeps normal tears on the eye, so they spill over or evaporate quickly and the dryness returns.

Is dry eye worse in winter?

Often, yes. Indoor heating lowers humidity and cold wind speeds up evaporation. A humidifier and wraparound glasses outdoors can help.

Do screens cause dry eye?

Screens don’t damage the eye, but they change how you blink. People blink far less while reading and concentrating, and on screens more blinks are incomplete. That exposes the eye surface for longer and worsens existing dry eye.

Sources

  1. TFOS DEWS III updates definitions and diagnostic processes in dry eye (opens in a new tab). Association of Optometrists news, June 2025.
  2. Distribution of aqueous-deficient and evaporative dry eye in a clinic-based patient cohort (opens in a new tab). Lemp et al., Cornea, 2012.
  3. Prevalence of Diagnosed Dry Eye Disease in the United States Among Adults Aged 18 Years and Older (opens in a new tab). Farrand et al., American Journal of Ophthalmology, 2017.
  4. Analysis of blink rate patterns in normal subjects (opens in a new tab). Bentivoglio et al., Movement Disorders, 1997.
  5. Blink Rate and Incomplete Blinks in Six Different Controlled Hard-Copy and Electronic Reading Conditions (opens in a new tab). Argilés et al., Investigative Ophthalmology & Visual Science, 2015.
  6. TFOS DEWS II iatrogenic report (opens in a new tab). Gomes et al., The Ocular Surface, 2017.
  7. TFOS DEWS III: Diagnostic Methodology (opens in a new tab). TFOS DEWS III, American Journal of Ophthalmology, 2025.
  8. Evidence-Based Strategies for Warm Compress Therapy in Meibomian Gland Dysfunction (opens in a new tab). Review of warm compress therapy in MGD, 2024.
  9. Ex vivo heat retention of different eyelid warming masks (opens in a new tab). Contact Lens & Anterior Eye, 2015.
  10. Interventions for chronic blepharitis (opens in a new tab). Lindsley et al., Cochrane Database of Systematic Reviews, 2012.
  11. Therapeutic benefits of blinking exercises in dry eye disease (opens in a new tab). Kim et al., Contact Lens & Anterior Eye, 2021.
  12. Over the counter (OTC) artificial tear drops for dry eye syndrome (opens in a new tab). Pucker et al., Cochrane Database of Systematic Reviews, 2016.
  13. FDA Approves Bausch + Lomb, Novaliq Dry Eye Disease Drug (opens in a new tab). BioSpace, May 2023.
  14. Alcon Announces FDA Approval of TRYPTYR (acoltremon ophthalmic solution) 0.003% for the Treatment of the Signs and Symptoms of Dry Eye Disease (opens in a new tab). Alcon press release, May 2025.
  15. Lotilaner Ophthalmic Solution 0.25% for Demodex Blepharitis: Randomized, Vehicle-Controlled, Multicenter, Phase 3 Trial (Saturn-2) (opens in a new tab). Saturn-2 phase 3 trial, Ophthalmology, 2023.
  16. FDA approves IPL device for treatment of dry eye disease signs (opens in a new tab). Healio, April 2021.
  17. Evaluation of an automated thermodynamic treatment (LipiFlow) system for meibomian gland dysfunction: a prospective, randomized, observer-masked trial (opens in a new tab). Finis et al., The Ocular Surface, 2014.
  18. Punctal occlusion for dry eye syndrome (opens in a new tab). Ervin et al., Cochrane Database of Systematic Reviews, 2017.
  19. Autologous serum eye drops for dry eye (opens in a new tab). Pan et al., Cochrane Database of Systematic Reviews, 2017.
  20. n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease (opens in a new tab). DREAM Study Research Group, New England Journal of Medicine, 2018.

Symvana guides are researched from primary sources and updated when the evidence changes. They’re for education and don’t replace an eye exam. Spotted an error? Email [email protected].

Read next

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