Korea's Health Insurance Review and Assessment Service recorded 2.378 million people treated for dry eye disease in 2022. By 2024 that was 4.7% of everyone covered by national health insurance — one person in twenty went to a clinic for it. 65.8% were women.
Gritty eyes after a long day at a screen are ordinary. The difficulty is that the same feeling arrives by two different routes. One is eye fatigue that resolves after a night's sleep; the other is a condition that stays and needs treating. And occasionally a third thing wears the same face: a sign that something other than your eyes is urgent. This guide separates the three using public-agency sources only.
What resolves, and what stays
The most practical test is time. Strain caused by screen work eases when you step away and is usually gone after sleep. If the same symptom is there when you wake up, or persists on a weekend away from screens, it is a different thing.
| Symptom | Screen work | Something persistent |
|---|---|---|
| Grittiness, foreign-body feeling | Worse during work, fades on a break | Present from the moment you open your eyes |
| Hazy vision | Clears within seconds of looking far away | Distance stays blurred too |
| Headache | Clusters in the afternoon, gone after sleep | Recurs regardless of time of day |
| Redness | Reddens after work, settles | Persists despite artificial tears |
| Watering | Unchanged | Runs for no reason (reflex tearing from dryness) |
| Glare, halos | Briefly, after night-time screen use | Ongoing trouble driving or at night |
Marks in the right-hand column will not be fixed by habit changes. On red eye, the Korea Disease Control and Prevention Agency's national health information portal states that "if there is pain or accompanying loss of vision, you must visit an ophthalmologist", and advises contact lens wearers to seek care if redness persists after stopping lens use, or does not improve with artificial tears.
Signs that mean go now
This section is not about habits. The signs below connect to conditions that can cost sight within hours or days, and every source quoted uses the words "immediately" or "emergency room".
| Sign | What it can be | The agency's wording | Where |
|---|---|---|---|
| Sudden severe eye pain + headache + nausea or vomiting + halos around lights | Acute angle-closure glaucoma | KDCA: "intraocular pressure rises sharply, producing severe eye pain, headache and loss of vision, sometimes with vomiting and nausea" | Emergency room |
| A sudden increase in floaters + flashes of light + a curtain across the field of vision | Retinal detachment | US National Eye Institute: "Retinal detachment is a medical emergency" | ER or an eye doctor immediately |
| Sudden loss of vision in one eye / one object appearing as two / half the visual field missing | Stroke | KDCA: "if even one of these appears suddenly, call 119 immediately and go to the emergency room" | 119 |
| Redness with pain or reduced vision | Corneal or uveal disease | KDCA: "you must visit an ophthalmologist" | Ophthalmologist |
The third row is the one people miss. Double vision and a missing half-field are listed by the KDCA as early stroke symptoms, not eye symptoms. Dismissing them as tiredness spends the treatment window. The rest of the stroke picture is in stroke warning signs and the 4.5-hour window, and choosing between an ER and a clinic is covered in emergency room or not.
Dry eye self-check — the ten questions
These are the self-check items published by Korea's National Health Insurance Service. The Service's own threshold: if two or three or more apply, dry eye disease is suspected and you should visit a clinic for appropriate treatment.
| # | Item |
|---|---|
| 1 | A gritty feeling, as if sand were in the eye |
| 2 | Heavy eyelids, with an ache that reaches the head |
| 3 | The eye reddens frequently |
| 4 | Contact lenses you wore comfortably start causing problems |
| 5 | Eyelids stick together on waking and are hard to open |
| 6 | Burning in dry or polluted environments |
| 7 | Long reading or computer work becomes difficult |
| 8 | Abnormal sensitivity to light, with sharp pain |
| 9 | A sensation that the eyes are falling out |
| 10 | Glare, with the eyes closing involuntarily |
Items 4 and 5 show what this list is for. Lenses that suddenly became uncomfortable and eyelids stuck together in the morning are a different order of signal from "my eyes are tired" — the same distinction as the right-hand column above.
For the environment, the Service recommends 60% indoor humidity and ventilating at least three times a day, because winter heating and summer air conditioning both strip indoor moisture. Seasonal humidity control is covered in managing humidity and mould in monsoon season.
Why eyes dry out — blinking falls to a third
The American Academy of Ophthalmology puts normal blinking at about 15 times a minute, falling to 5–7 times a minute at a computer or digital screen. Blinking is what spreads the tear film back across the eye's surface, so cutting it to a third extends the time the surface spends drying.
Which means the fix is not artificial tears but blinking itself. Deliberately mixing in a few slow, complete blinks during screen work changes the surface condition on its own. Half-closed, shallow blinks do not spread the film fully.
For the same reason screen height matters. A gaze angled upward opens the lids wider, exposes more surface, and dries it faster. The "10–15° below horizontal" figure in the guidance below exists for exactly this.
The numbers Korea's labour guidance already fixes
Screen-work environments have numbers set in statute and in occupational safety guidance — the VDT Work Management Guidelines for display screen equipment and KOSHA GUIDE E-G-3-2025. These are better to work from than the recommendations circulating online.
| Item | Standard | Source |
|---|---|---|
| Distance from eyes to screen | 40cm or more | VDT Work Management Guidelines |
| Line of sight | 10–15° below horizontal | VDT Work Management Guidelines |
| Illuminance — dark screen background | 300–500 lux | VDT Work Management Guidelines |
| Illuminance — light screen background | 500–700 lux | VDT Work Management Guidelines |
| Continuous working time | Not to exceed one hour | KOSHA GUIDE E-G-3-2025 |
| Break | 5–10 minutes every hour | KOSHA GUIDE E-G-3-2025 |
| Indoor humidity | 40–70% | KOSHA GUIDE E-G-3-2025 |
| Indoor temperature | 18–24°C | KOSHA GUIDE E-G-3-2025 |
Illuminance has two rows because the real issue is the contrast between screen and surroundings. A dark-background screen in a bright room forces the eye to keep re-adapting. If you mostly read white documents, brighten the room; if you live in a dark-themed editor, dim it slightly. That is closer to the guidance than a single fixed number.
"Not to exceed one hour" is the text of the guidance, not a suggestion. Sitting through two hours at a screen is already outside the standard. Neck and shoulder work you can do at the desk is in five stretches for forward-head posture.
Where the 20-20-20 rule actually comes from
It is the most widely repeated piece of advice here, and checking the source shows it is not from a Korean public agency. The original is eye-health guidance from the National Eye Institute, part of the US National Institutes of Health.
The NEI's sentence: "Rest your eyes by taking a break every 20 minutes to look at something about 20 feet away for 20 seconds."
What the rule targets is not dryness but the focusing muscle. Holding focus on a near screen keeps the muscle that adjusts the lens contracted; looking into the distance relaxes it. Twenty seconds is the time that relaxation takes, and 20 feet is effectively treated as infinity — it does not have to be out of a window. The far wall of the office is usually enough.
But the rule does nothing about blinking. Releasing focus and re-spreading the tear film are separate problems. Look far away every 20 minutes, and add a few complete blinks while you do it — that covers both routes.
On blue-light filtering glasses, this article will not assert an effect either way. No official Korean public-agency document recommending or dismissing them could be found. The only thing that can be said within what was verified is that blue light appears nowhere in the guidance or the self-check above.
When to see a doctor
The decision comes down to four lines.
- Emergency, now — sudden severe eye pain with headache, vomiting and halos; or a sudden increase in floaters with flashes and a curtain across your vision. Not something to leave until tomorrow.
- Call 119 now — sudden loss of vision in one eye, one object appearing as two, or half the visual field gone. It presents as an eye problem but the KDCA lists it under early stroke symptoms.
- An eye clinic this week — if two or three or more of the ten self-check items apply, or if redness or pain persists despite artificial tears and stopping lens wear.
- Habits first — if none of the above and the fatigue clears with sleep. Set 40cm of distance, 10–15° downward gaze, no more than an hour continuously and 40–70% humidity; if it still persists, move to line 3.
If you have held line 4 for a couple of weeks and the morning symptoms are unchanged, you have your answer: it is not a habit problem. That is the point to book an appointment. If whole-body fatigue accompanies it, the signals a thyroid sends is worth a look.
Sources and where to verify
- Health Insurance Review and Assessment Service — disease statistics, dry eye disease (2.378 million treated in 2022; 4.7% of the insured; 65.8% women)
- National Health Insurance Service — dry eye self-check and daily management (two or three items means see a clinic; 60% humidity; ventilate three times a day)
- KDCA national health information portal — glaucoma (acute angle-closure: eye pain, headache, vision loss, vomiting, halos)
- KDCA national health information portal — early stroke symptoms (loss of vision in one eye, double vision, half-field loss → 119)
- KDCA national health information portal — red eye (pain or vision loss means an ophthalmologist)
- National Eye Institute (NIH) — the 20-20-20 rule, original wording / retinal detachment emergency symptoms
- American Academy of Ophthalmology — computer use and blinking (15 per minute falling to 5–7)
Written as of July 2026. The VDT environment figures are taken from the VDT Work Management Guidelines and KOSHA GUIDE E-G-3-2025; Korea's statute portal blocks automated access, so the originals could not be read directly and were cross-checked against agency republications instead. In addition, the KDCA has no dedicated page on VDT syndrome or computer vision syndrome, and no Korean public-agency source stating the 20-20-20 rule or blink-rate figures could be found — those are therefore cited to US agencies. The KDCA's retinal detachment page redirected and could not be opened, so only the National Eye Institute is cited there. This article does not replace a diagnosis; if lines 1–3 above apply to you, stop reading and get seen.
