Dry, tired eyes from screens in an air-conditioned office?

If your eyes feel dry and tired after a day at a screen in an air-conditioned office, the UK's NHS lists both air-conditioned rooms and looking at a screen for a long time without a break among the things that make dry eyes more likely. Start with where you sit and how you work: move out of the direct airflow of the vent or fan, take a short break from the screen every hour, and keep the screen just below eye level. In a Chiang Mai University study of 261 workers in air-conditioned offices, 27.2% had eye symptoms such as irritation, dryness, watering, itching or redness, and the odds rose with every hour of screen time beyond 7 hours a day and with higher formaldehyde in the office air. If your eyes still feel dry after a few weeks of changes, see an optician or doctor.

This article is about the office: air conditioning, dry air and long screen hours. For the 20-20-20 habit and screen set-up in more detail, see Tired, dry eyes from screens all day. What should I do? If you wear contact lenses, see My eyes feel dry with contact lenses. What can I do?

Why do my eyes feel dry in an air-conditioned office?

Air moving across the eye

The UK's NHS lists spending time in air-conditioned or heated environments, and windy, dry or dusty conditions among the things that make dry eyes more likely, and advises not spending too long in air-conditioned or heated rooms. The US National Eye Institute (NEI) suggests avoiding smoke, wind and air conditioning if your eyes feel dry. Most office workers cannot leave the air conditioning, but you can usually change where the air hits you.

You blink less at a screen

In a study of 51 volunteers in Germany, people blinked about 15.5 times a minute during a conversation and about 5.3 times a minute while working at a screen. The study measured blinking in people with healthy eyes; it did not find a link between how often they blinked and their tear measurements, so it shows how much blinking drops at a screen rather than proving that this alone dries the eyes.

Long hours without a break

The NHS also lists looking at computer screens for a long time without a break. The UK's Health and Safety Executive (HSE) says screen work does not cause permanent damage to the eyes, but long spells of it can lead to tired eyes, discomfort and headaches.

How common are dry, irritated eyes among Thai workers?

What Thai studies found

Reading the numbers

The figures range from about 8% to over 70% because each study used a different questionnaire, a different definition and a different group of people. Most were done in Chiang Mai or Bangkok, at one point in time, and relied on what people reported. What they share is the pattern: long screen hours, contact lenses and stress keep appearing alongside dry, irritated eyes. These are associations, not proof that one causes the other.

Is the air in a Thai office too dry?

What humidity studies show

A study by Jones and colleagues at Harvard measured humidity for a year in 43 office buildings in China, India, Mexico, Thailand, the UK and the US. During weekday office hours, 42% of readings were below 40% relative humidity. Humidity tended to be lower in less tropical regions, in winter and late in the workday, and higher humidity went with fewer reports of a dry, irritated throat and skin among women.

In Chiang Mai offices, the air was not very dry

In the Chiang Mai University offices, average temperature was about 23.4°C and relative humidity about 62%, measured once in October, between the rainy and cool seasons. That is not low, but it is one set of offices at one time of year, and every air-conditioned room is different. In that study, the factors that went with eye symptoms were longer screen time and higher formaldehyde in the air. If the air in your office or home feels dry, both the NHS and NEI suggest using a humidifier if the air is dry.

What can I do at my desk?

Move out of the airflow

• Look at where the vent, split unit or fan is pointing. If it blows across your face, ask to angle the louvres or move your desk.
• Do not sit with a desk fan pointed at your face.
• On the way to work, the NEI suggests wraparound sunglasses outside to keep wind and dust off your eyes.

Take short breaks often

The HSE advises that short, frequent breaks are better than longer, less frequent ones: 5 to 10 minutes every hour is better than 20 minutes every 2 hours. Breaks should let you get up and move around. Going to a meeting or making a phone call away from the screen counts as a change of activity. For the 20-20-20 habit, see our article on screen time and your eyes.

Set up the screen

The NHS advises making sure your computer screen is just below eye level. The HSE says you can help your eyes by checking the screen is well positioned and properly adjusted, and making sure the lighting is suitable.

For tips on blinking and resting your eyes at a screen, see Tired, dry eyes from screens all day. What should I do?

What can I do at home and in daily life?

Clean your eyelids

The NHS suggests cleaning your eyelids every day: press a flannel soaked in warm (not hot) water gently on the area around your eyes, massage the eyelids gently, then wipe away any oil, crusts or dust with cotton wool soaked in warm water.

Smoke, sleep and everyday habits

The NHS advises not smoking or drinking too much alcohol, and not spending too long in smoky, dry or dusty places. The NEI's list also includes general habits for the whole body: getting about 7 to 8 hours of sleep a night and drinking plenty of water (it suggests 8 to 10 glasses a day).

Medicines and eye drops

The NHS advises not stopping a prescribed medicine without medical advice, even if you think it is causing your symptoms. A pharmacist can tell you what you can do yourself, whether you can buy something to help, and whether you need to see an optician or doctor. If you use any health products regularly, tell your doctor or pharmacist.

When should I see a doctor about dry eyes at work?

See an optician or doctor if

• your eyes still feel dry after trying these changes for a few weeks
• the shape of your eyelids has changed
• dry eyes are getting in the way of your work or daily life (the NEI advises telling your doctor)

Get urgent help if

• your eye is painful and red
• your eye is red and you wear contact lenses

Go to an emergency department straight away if

• your sight changes, such as wavy lines, flashing or loss of vision
• it hurts to look at light
• you have a red eye, a severe headache and feel sick
• your eye is very dark red
• you have injured your eye, or something is stuck in it

If you work with screens, the HSE notes that in the UK an employer must arrange an eye test for screen users who ask for one. In Thailand, ask your workplace whether eye checks are part of your annual health check. For red, itchy eyes in the haze season, see Itchy, red eyes in PM2.5 haze season: what can I do?