The 20-20-20 Rule for Eye Strain: How to Actually Use It

If your eyes feel tired, dry or blurry by the end of a screen day, you are in very good company. Eye doctors have a simple habit they recommend for it, and it is easy to remember because it is all about the number 20.

What is the 20-20-20 rule?

The American Academy of Ophthalmology (AAO) puts it like this: every 20 minutes, shift your eyes to look at an object at least 20 feet away, for at least 20 seconds.

In metric terms, that is roughly 6 metres. A window, the far end of the room or a corridor all work. You do not need to measure: the point is to look properly into the distance, not at the wall just behind your monitor.

What is digital eye strain?

Digital eye strain, also called computer vision syndrome, is the group of eye and vision complaints that come from long periods of using computers, tablets, e-readers and phones. According to the AAO, common symptoms include blurred vision and achy, tired or uncomfortable eyes, along with dryness, watering and stinging. Some people also get headaches or tired facial muscles from squinting.

The AAO's EyeWiki also lists neck pain, shoulder pain and headache among the symptoms that can come with heavy screen use, which is one reason screen distance and posture tend to come up together.

Why it happens

Two things do most of the work. First, you blink less. The AAO notes that people normally blink about 15 times a minute, and that this drops when using screens, which lets the surface of the eye dry out.

Second, you hold your focus at one close distance for a long time. Looking far away for a moment lets your eyes relax that close focus, and it is a natural moment to blink a few times too.

Is it harmful?

The reassuring part: the AAO says eye strain does not injure the eye and does not cause permanent damage. It also says the idea that long screen use permanently damages your eyes is not true. The discomfort is real, though, and worth reducing.

How to make the rule stick

The rule is easy to agree with and very easy to forget. Twenty minutes disappears when you are concentrating. A few ways to make it automatic:

Use a reminder. A phone timer works, though a quiet desktop notification is less disruptive.
Pick your distance spot in advance, such as a window or a picture on the far wall, so you do not have to think about where to look.
Pair it with something you already do, like sending an email or finishing a meeting.
Blink deliberately a few times while you look away.
Every hour or so, turn the 20-second look into a proper break: stand up, stretch, walk.

Other screen habits that help

The AAO and ergonomics bodies suggest a few more changes alongside the 20-20-20 rule:

Sit about an arm's length from the screen. The AAO suggests around 25 inches (about 64 cm).
Position the screen so you look slightly down at it.
Match screen brightness to the room. If the screen glows much brighter than its surroundings, your eyes work harder.
Reduce glare with a matte screen filter, and keep air vents from blowing at your face.
Use artificial tears when your eyes feel dry, and consider a humidifier in a dry, warm room.
Keep your glasses or contact lens prescription up to date, and ask about computer glasses if you struggle to see the screen.

A reminder that does not nag

The hardest part of the 20-20-20 rule is remembering it. Upsaro includes a 20-20-20 reminder alongside its posture, stretch, water and walk reminders, delivered as a normal system notification on Windows or Mac. It also uses your webcam, on your own computer, to notice when you lean in close to the screen. It is a wellness tool, not a medical device.

When to see an eye doctor

If eye strain continues after you have adjusted your workspace and habits, the AAO recommends seeing an eye doctor. Tell them when the symptoms happen and how long they last. They may check for dry eye and whether you need a new prescription.