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 12 min readHow we research
On this page
  1. What dry eye actually is
  2. Dry eye symptoms, including the confusing ones
  3. The two main types
  4. What causes dry eyes
  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. That’s a simplification: researchers now see the mucin and water as one gel-like layer under the oil1 Willcox et al., The Ocular Surface, 2017 (opens in a new tab). TFOS DEWS II Tear Film Report., but the three parts are still the easiest way to see what can go wrong.

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 other2 TFOS DEWS III, American Journal of Ophthalmology, 2025 (opens in a new tab). TFOS DEWS III: Diagnostic Methodology.. Symptoms are 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.

Dry eye 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

Blur is one symptom researchers have measured. In a small study, people with dry eye saw much less sharply after keeping their eyes open for 10 to 20 seconds without blinking, while vision in people without dry eye held steady3 Goto et al., American Journal of Ophthalmology, 2002 (opens in a new tab). Impaired functional visual acuity of dry eye patients.. Our guide to dry eyes and blurry vision explains why it happens and which kinds of blur need prompt care.

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, 86% of the dry eye patients whose type could be identified showed signs of this meibomian gland dysfunction4 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, with certain medications and with autoimmune conditions such as Sjögren’s, in which the immune system attacks the glands that make tears and saliva5 US National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health (opens in a new tab). Sjögren’s Disease.. Menopause is often assumed to play a part too. Hormones do act on the tear and oil glands, but an expert review found that definitive evidence linking menopause to dry eye is lacking6 Sullivan et al., The Ocular Surface, 2017 (opens in a new tab). TFOS DEWS II Sex, Gender, and Hormones Report.. Our guide to dry eyes in perimenopause and menopause covers what’s known.

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, 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 dry eyes

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

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 sign2. 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 may be safe and effective, though the evidence behind them is low quality18 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

For how these compare, including dosing, side effects and generics, see our guide to prescription dry eye drops.

In a clinic

For what these cost and how to choose a clinic, see our guide to dry eye treatments and their costs.

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 dry eye quiz

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

Omega-3 supplements. Mixed evidence Many clinicians recommend fish oil for dry eye. The DREAM trial put it to the test: 535 people with moderate to severe dry eye took either 3,000 mg of omega-3 a day or an olive oil placebo for a year, and both groups improved by about the same amount31 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.. Most earlier trials, many of them far smaller, had found a benefit. But they differed from DREAM in who took part, the dose and the placebo, and when the DREAM researchers looked at groups like the ones those trials enrolled, they found no evidence of a benefit there either31. So omega-3 shouldn’t be your first move.

Vitamin supplements. A 2026 systematic review of vitamin pills for dry eye found 13 studies, of vitamins A, B1, B12 and D, and judged none of them high quality. The studies weren’t well controlled or large enough, followed people only briefly and used different doses, and the authors concluded that the research doesn’t support taking vitamins routinely for dry eye32 Heidari et al., Ophthalmic and Physiological Optics, 2026 (opens in a new tab). The Efficacy of Oral Vitamin Supplementation in Dry Eye Disease: A Systematic Review..

Drinking more water. Weak evidence Staying hydrated is good for you, but there’s no good evidence that extra water helps dry eye unless you’re dehydrated.

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

Is dry eye syndrome the same as dry eye disease?

Yes. Dry eye syndrome is the older name. The 2025 international definition calls it a disease rather than a syndrome, but both names describe the same condition.

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. Our screen eye strain guide covers the setup and habits that help.

Can dry eyes cause blurry vision?

Yes. In a small study, people with dry eye saw much less sharply after keeping their eyes open for 10 to 20 seconds without blinking, while people without dry eye didn’t. People blink less while reading, driving or looking at a screen, so that’s when blur can show up, and a blink often clears it for a moment. A sudden change in vision is different: see an eye doctor promptly.

Do vitamins help dry eye?

There isn’t enough good evidence to recommend them. A 2026 review found 13 studies of vitamin A, B1, B12 and D supplements for dry eye and judged none of them high quality: they were poorly controlled, too small or too short. Omega-3 fish oil, which has been tested in a large trial, did no better than an olive oil placebo.

Sources

  1. TFOS DEWS II Tear Film Report (opens in a new tab). Willcox et al., The Ocular Surface, 2017.
  2. TFOS DEWS III: Diagnostic Methodology (opens in a new tab). TFOS DEWS III, American Journal of Ophthalmology, 2025.
  3. Impaired functional visual acuity of dry eye patients (opens in a new tab). Goto et al., American Journal of Ophthalmology, 2002.
  4. Distribution of aqueous-deficient and evaporative dry eye in a clinic-based patient cohort (opens in a new tab). Lemp et al., Cornea, 2012.
  5. Sjögren’s Disease (opens in a new tab). US National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health.
  6. TFOS DEWS II Sex, Gender, and Hormones Report (opens in a new tab). Sullivan et al., The Ocular Surface, 2017.
  7. 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.
  8. Analysis of blink rate patterns in normal subjects (opens in a new tab). Bentivoglio et al., Movement Disorders, 1997.
  9. 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.
  10. TFOS DEWS II iatrogenic report (opens in a new tab). Gomes et al., The Ocular Surface, 2017.
  11. The TFOS International Workshop on Contact Lens Discomfort: executive summary (opens in a new tab). Nichols et al., Investigative Ophthalmology & Visual Science, 2013.
  12. Nocturnal lagophthalmos: an overview and classification (opens in a new tab). Latkany et al., The Ocular Surface, 2006.
  13. Impact of Positive Airway Pressure and Mask Leakage on Dry Eye and Glaucoma Risk in Obstructive Sleep Apnea: A Cross-Sectional Analysis (opens in a new tab). Wang et al., Biomedicines, 2025.
  14. Evidence-Based Strategies for Warm Compress Therapy in Meibomian Gland Dysfunction (opens in a new tab). Lee, Ophthalmology and Therapy, 2024.
  15. Ex vivo heat retention of different eyelid warming masks (opens in a new tab). Lacroix et al., Contact Lens & Anterior Eye, 2015.
  16. Interventions for chronic blepharitis (opens in a new tab). Lindsley et al., Cochrane Database of Systematic Reviews, 2012.
  17. Therapeutic benefits of blinking exercises in dry eye disease (opens in a new tab). Kim et al., Contact Lens & Anterior Eye, 2021.
  18. 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.
  19. Improved Dry Eye Drugs for 2025 and Beyond (opens in a new tab). American Academy of Ophthalmology.
  20. Topical cyclosporine A therapy for dry eye disease (opens in a new tab). Priyadarshini et al., Cochrane Database of Systematic Reviews, 2026.
  21. MIEBO (perfluorohexyloctane ophthalmic solution) (opens in a new tab). FDA prescribing information: Miebo, via DailyMed.
  22. Efficacy and Safety of Perfluorohexyloctane in Evaporative Dry Eye Disease Associated With Meibomian Gland Dysfunction: A Systematic Review and Meta-Analysis of Randomized Controlled Trials (opens in a new tab). Guedes et al., Cureus, 2024.
  23. TRYPTYR (acoltremon ophthalmic solution) 0.003% (opens in a new tab). FDA prescribing information: Tryptyr, via DailyMed.
  24. TYRVAYA (varenicline solution) nasal spray (opens in a new tab). FDA prescribing information: Tyrvaya, via DailyMed.
  25. 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.
  26. Intense pulsed light device for managing dry eye (Lumenis Stellar M22), granted February 2021 (opens in a new tab). US FDA, De Novo decision DEN200028, 2021.
  27. Effectiveness and safety of intense pulsed light therapy for dry eye symptoms due to meibomian gland dysfunction: a systematic review and meta-analysis (opens in a new tab). Peira et al., Acta Ophthalmologica, 2025.
  28. LipiFlow for the treatment of dry eye disease (opens in a new tab). Pucker et al., Cochrane Database of Systematic Reviews, 2024.
  29. Punctal occlusion for dry eye syndrome (opens in a new tab). Ervin et al., Cochrane Database of Systematic Reviews, 2017.
  30. Autologous serum eye drops for dry eye (opens in a new tab). Pan et al., Cochrane Database of Systematic Reviews, 2017.
  31. 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.
  32. The Efficacy of Oral Vitamin Supplementation in Dry Eye Disease: A Systematic Review (opens in a new tab). Heidari et al., Ophthalmic and Physiological Optics, 2026.

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 hello@symvana.com.

Read next

GuideThe best eye drops for dry eyes, by typeThere’s no single best eye drop for dry eyes. How to choose by type, when to go preservative-free, which ingredients help, and our picks for day and night.GuideWarm compresses, done properlyWhy warm compresses help evaporative dry eye, why a washcloth usually fails, the right temperature and time, and how to choose a heated eye mask.GuideDry eye treatments beyond drops, with costsPrescription dry eye drops and clinic treatments like IPL, LipiFlow and punctal plugs: how they work, the evidence, typical costs and choosing a clinic.