The 20-20-20 rule: what a 2023 study actually found

The 20-20-20 rule is simple: every 20 minutes, look at something about 20 feet (6 metres) away for 20 seconds. The American Academy of Ophthalmology includes it in its advice for people who spend long hours at a screen. It's easy to remember, which is part of why it's everywhere.

For a long time, though, there was little direct research on the rule itself. A study published in the journal Contact Lens and Anterior Eye (volume 46, 2023) set out to test it. Here is what it did and what it found, in plain terms.

How the study worked

• Who took part. 29 computer users who already had symptoms of screen-related eye strain.
• What changed. Software on each person's laptop used the webcam to track breaks, gaze and blinking, and sent personalised reminders to follow the 20-20-20 rule.
• When they were checked. At the start, after two weeks of reminders, and again one week after the reminders were switched off.
• What was measured. Symptom questionnaires for eye strain and dry eye, a wide range of eye focusing and coordination tests, and tests of the tear film and eye surface.

It's worth knowing that this was a before-and-after study in a small group, not a large randomised trial with a separate comparison group. That limits how far the results can be stretched.

What changed

• Breaks. With reminders, people took more breaks per day, and both their stretches of computer work and their breaks got shorter.
• Symptoms. Scores for eye strain and dry eye symptoms went down while the reminders were running.
• One focusing measure. Of the many binocular vision tests, only one, accommodative facility (how quickly the eyes switch focus), changed.

What didn't change

• The eye surface and tears. None of the tear film or eye surface measures changed over the two weeks.
• Most focusing and coordination tests. Apart from the one above, these stayed the same.
• The effect after stopping. One week after the reminders were switched off, the drop in symptom scores was no longer there.

The authors concluded that the rule was an effective way to reduce symptoms in their group, and that two weeks was too short to see changes in the eye surface or binocular vision.

What this means in practice

The study fits a common-sense reading of the rule: regular breaks make long screen sessions feel more comfortable while you keep taking them. It doesn't show that breaks repair or change anything in the eye, and the benefit faded once people stopped.

Some practical takeaways:

• Reminders matter. People in the study had software prompting them. Most of us forget breaks when we're focused. A timer, a calendar nudge or a break app can do the same job.
• It's a habit, not a fix. If breaks feel helpful, the study suggests they only keep helping while you keep doing them.
• Pair it with the basics. The AAO also suggests keeping the screen about 25 inches (an arm's length) away with your gaze slightly downward, cutting glare and matching screen brightness to the room.
• Blink during breaks. The AAO notes that focusing on a screen can reduce blinking by a third to a half, which can dry out the eyes.

You can read our step-by-step page on the 20-20-20 rule and our wider guide to screen eye strain.

Seeing whether it helps you

Your experience may differ from a group average. If you want to know whether breaks make a difference for you, note your screen hours and how your eyes feel at the end of each day for a couple of weeks, with and without regular breaks. A journal like Ocufuse can hold these notes, but a paper diary works too. Either way, it's a personal record, not a measurement of your eyes.

When to see someone

Breaks are a comfort habit. They're not a substitute for an eye test. Book an appointment with an optometrist or eye doctor if:

• Strain, headaches or tired eyes carry on despite regular breaks
• Your vision is blurred and doesn't clear when you rest
• Your eyes are often dry, gritty or watery
• Your last eye test was a while ago, or your glasses no longer feel right