Dry eye happens when the tear film either evaporates too fast or is produced in too small a quantity. Symptoms include burning, grittiness, redness, fluctuating blur that clears when you blink — and, confusingly, excessive watering. It is diagnosed with tear-film break-up time, Schirmer testing and meibomian gland assessment, and treated with lubricants, lid hygiene, and where needed punctal plugs or anti- inflammatory drops. Screen users should follow the 20-20-20 rule.
The tear film is three layers, not one
Tears are not simply water. A healthy tear film has an inner mucous layer that helps it stick to the eye, a middle watery layer, and a thin outer oily layer produced by the meibomian glands in your eyelids, which stops the water evaporating.
Dry eye is usually a failure of that oily layer — not of tear production. The tears are there; they simply evaporate before they do their job. This is why "just use more drops" so often fails, and why treatment aimed at the eyelids works better than treatment aimed only at the eye.
Why watering is a dry eye symptom
When the tear film breaks down, the exposed surface stings, and the eye responds with a flood of reflex tears. These are watery and lack the oily layer, so they run over the lid instead of coating the eye. The eye ends up drenched and dry at the same time.
Common causes
- Screen work — blinking drops by more than half when you stare at a display
- Air conditioning, fans and dry air
- Meibomian gland dysfunction — blocked oil glands along the lid margin
- Age and hormonal change, particularly after menopause
- Contact lens wear
- Medications — antihistamines, some antidepressants, some blood pressure tablets
- After LASIK — usually temporary
- Autoimmune conditions such as Sjogren's syndrome, rheumatoid arthritis and thyroid disease
How we assess it
- Tear break-up time — how many seconds the tear film survives before it fragments
- Schirmer test — measures how much tear volume is produced
- Meibomian gland assessment — expressing the lid margin to see whether the oil is flowing or blocked
- Ocular surface staining — a dye that shows where the surface has been damaged
Treatment
Treatment is matched to the cause, and it is layered rather than one-size-fits-all:
- Preservative-free lubricants, used on a schedule rather than only when uncomfortable
- Warm compresses and lid hygiene — unglamorous, done nightly, and the treatment that helps most in meibomian gland dysfunction
- Anti-inflammatory drops for surface inflammation, on prescription
- Punctal plugs — tiny inserts that block tear drainage so your own tears stay on the eye longer
- Omega-3 supplementation and management of any contributing systemic condition
Screen habits that actually help
- 20-20-20: every 20 minutes, look 20 feet away for 20 seconds
- Position the screen below eye level — looking slightly down narrows the exposed eye surface
- Blink fully and deliberately; a half-blink does not resurface the eye
- Keep air conditioning vents and fans from blowing directly at your face
- Increase text size rather than leaning in
Frequently asked questions
Why do my eyes water if they are dry?
Watering is one of the commonest signs of dry eye, not evidence against it. When the tear film breaks down, the exposed surface irritates the eye and triggers a flood of reflex tears. These lack the oily layer that stops them evaporating, so they spill over the lid instead of coating the eye.
What is the 20-20-20 rule for screen use?
Every 20 minutes, look at something about 20 feet away for at least 20 seconds. Screen work halves the blink rate, which is what dries the eye. Looking away restores a full blink and relaxes the focusing muscle at the same time.
Are lubricating eye drops safe to use every day?
Preservative-free drops are safe several times a day, long term. Drops containing preservatives are best limited to about four times daily, because preservative exposure can itself irritate the surface with heavy use.