Dry eyes and screen work: why it happens and what helps

Burning, scratching, a gritty feeling as if there were sand in your eye – often towards the end of a long day at the laptop. Behind this there is frequently a tear film that gets thrown off balance during screen work. The good news first: according to the American Academy of Ophthalmology (AAO), long hours at a screen do not permanently damage your eyes, and a few simple habits can make a noticeable difference. Persistent symptoms are worth having checked, though: according to the AAO, chronic dry eye can sometimes point to eyelid disease or an autoimmune condition.

Blinking less, and less completely: what happens at the screen

Every blink spreads a fresh tear film, including its oily and mucous components, helps tears drain away and keeps the cornea moist. At a screen, we often blink much less. In a study of office workers published in the New England Journal of Medicine in 1993, the blink rate was around 22 per minute when relaxed, 10 when reading a book and just 7 when reading on a screen.

A later finding adds an interesting twist. When researchers in 2014 had people read identical text on paper and on a monitor – same size, same contrast, same distance – participants blinked about equally often in both cases (14.9 times per minute on screen and 13.6 on paper). So the screen alone does not explain the effect. Concentration seems to play a major role: in a laboratory experiment, the blink rate during a demanding computer task was 69 per cent lower than during a passive one. Afterwards, participants briefly blinked more – as if to catch up.

What did change at the screen: the lids more often failed to close fully. In the 2014 study, 7.0 rather than 4.3 per cent of blinks were incomplete. In another study from 2015, cited in the 2023 report of the Tear Film & Ocular Surface Society (TFOS), this share was 14.5 per cent when reading on digital devices and 5 per cent on paper. And when young adults read on a smartphone for an hour, the number of incomplete blinks rose from a median of 6 to 15 per minute.

The tear film: three layers working together

In simplified terms, the AAO describes the tear film as three layers:

• Oily (lipid) layer: the outermost layer smooths the surface and slows evaporation. The oil comes from the meibomian glands in the eyelids.
• Watery layer: the bulk of the tear film; it rinses the eye and carries away dust and debris.
• Mucus (mucin) layer: it allows the watery layer to coat the surface of the eye evenly.

Blinking less often means less tear fluid is spread. With incomplete blinks, according to the TFOS report, the tear film is also thought to spread less well, particularly over the lower third of the cornea, and the lipid layer can become thinner. When the meibomian glands become blocked or stop working properly, the AAO calls this meibomian gland dysfunction. With too little oil, the tear film can then evaporate more quickly.

By the way, watery eyes do not rule out dry eye. According to the AAO, irritated dry eyes often produce extra tears – which sounds paradoxical but is typical.

The 20-20-20 rule – and what the research says

A well-known habit is the 20-20-20 rule, which the AAO, among others, recommends: every 20 minutes, look at something at least 20 feet (around 6 metres) away for at least 20 seconds.

How strong is the evidence? According to the TFOS report, only a few studies have tested it so far. In one of them, software reminded 29 computer users with symptoms to take breaks according to the 20-20-20 rule. After two weeks they took more, but shorter, breaks and reported fewer symptoms – though the study had no control group. The tear film showed no measurable change, and one week after the reminders were switched off the improvement had gone – so if the rule helps, it probably does so only as a firm habit.

Much the same applies to blinking exercises. In people with dry eye, one study found that deliberate ten-second blinking cycles every 20 minutes over four weeks were associated with fewer symptoms, a more stable tear film and fewer incomplete blinks – but about a quarter of participants dropped out, and the routine was fairly demanding, at an average of more than 25 cycles a day. The TFOS report also notes that expectations can skew such results when participants know which treatment they are receiving. A practical middle ground: make a point of blinking often – as a reminder, the AAO even suggests a sticky note on your monitor.

Setting up your workspace: screen height, distance, room air

Screen slightly below eye level. The AAO advises positioning the screen so that your gaze is directed slightly downwards – not straight ahead and not upwards. The reason: the wider your eyes are open, the more surface is exposed. According to a measurement cited in the TFOS report, around 1.2 square centimetres of eye surface was exposed with a lowered gaze, as when reading a book – twice as much when reading on a computer, and almost three times as much when looking upwards. Whether a lower monitor also eases symptoms has not been shown consistently in studies so far.

Distance. The AAO suggests about 25 inches, or roughly 64 centimetres – about an arm’s length.

Brightness and glare. Match the screen brightness to the surrounding light and reduce reflections, for example with a matte screen filter. According to the TFOS report, several studies found fewer symptoms when glare was reduced.

Room air. According to the TFOS report, low humidity and air conditioning in the office increased the risk of dryness symptoms, while desktop humidifiers improved symptoms and tear film stability. In a one-hour trial with 44 computer users, considerably more participants reported greater comfort with a small USB humidifier – even though humidity rose only slightly. The AAO, too, suggests a humidifier if you often spend time in dry, warm rooms.

Glasses and contact lenses. According to the TFOS report, any refractive error should be fully corrected for the relevant working distance. Contact lens wearers can, as the AAO suggests, switch to their glasses from time to time. Spectacle lenses with blue-light filters, on the other hand, have not been shown to be effective against digital eye strain, according to the TFOS report (see blue-light glasses).

Artificial tears: what to look for

Artificial tears are available without a prescription and, according to the AAO, can be used as often as you need them. If you use drops more than six times a day or are allergic to preservatives, the AAO advises choosing preservative-free products.

A Cochrane review from 2016, covering 43 randomised trials with 3,497 participants, concluded that over-the-counter artificial tears may be safe and effective and that most products may work similarly well. The quality of the evidence, however, was low. According to the TFOS report, few studies have looked specifically at screen work.

If drops are not enough, an ophthalmologist can suggest other options – according to the AAO, these include warm compresses, eyelid massage and lid cleansing for meibomian gland problems, prescription eye drops, or tiny plugs that close the tear drainage channels.

When to see an ophthalmologist

Not every dry feeling has to do with screens. According to the AAO, factors that can contribute to dry eye include age, hormonal changes (for example after menopause), eyelid inflammation (blepharitis), conditions such as Sjögren’s syndrome, rheumatoid arthritis or thyroid disease, certain medications (for instance antihistamines or beta blockers), long-term contact lens wear and LASIK surgery.

Have your eyes examined by an ophthalmologist if:

• your symptoms persist or get worse,
• they affect your daily life,
• over-the-counter drops do not help enough,
• your vision keeps getting blurry or your eyes are constantly red or watery.

If you have pain, marked redness, pronounced sensitivity to light or a sudden deterioration in your vision, do not wait – see an ophthalmologist or an emergency service the same day. If you wear contact lenses, take them out straight away: according to the AAO, such signs can point to an infection or another serious eye problem.

At My Laser Vision in Wallisellen, a tear film examination and a screen-work eye assessment are part of our ophthalmology services.