Digital Eye Strain at Your Desk: The 20-20-20 Rule and Other Ophthalmologist Tips
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How we wrote this: A summary of patient-education pages from the American Academy of Ophthalmology (AAO), linked below. It is general information, not medical advice. If your eyes are consistently red, painful or light-sensitive, or your vision changes, see an eye doctor.
Long days at a screen can leave your eyes tired, dry and blurry by late afternoon. The good news, per the AAO, is that screens don't permanently damage your eyes. The discomfort is real, though, and mostly preventable.
Why screens tire your eyes
The AAO's page on computers, digital devices and eye strain says people normally blink about 15 times a minute, but only about 5 to 7 times a minute while using screens. Blinking is how the eye's surface stays moist, so less blinking leads to dryness, stinging and blur. The AAO says this strain is no different from what you feel after long stretches of reading or other close work.
The 20-20-20 rule
The AAO's blue light page calls regular breaks the best protection, using the 20-20-20 rule:
Every 20 minutes, look at something at least 20 feet away for at least 20 seconds.
A recurring timer works well. So does a window or a far wall you can glance at from your chair.
Set up your screen
From the AAO's tips:
| Tip | What the AAO says |
|---|---|
| Distance | Sit about 25 inches from the screen, roughly arm's length |
| Height | Position the screen so your gaze is slightly downward, not straight ahead or up |
| Brightness | Match screen brightness to the light around you; a screen brighter than its surroundings makes your eyes work harder |
| Contrast | Try increasing contrast |
| Glare | Consider a matte screen filter to cut glare |
| Dry air | Use artificial tears when your eyes feel dry, and consider a humidifier in a dry, warm room |
Our home office ergonomics checklist covers chair and keyboard height, which affect where your eyes end up.
Glasses: computer glasses vs. blue light glasses
These are different things, and the AAO treats them differently:
- Computer glasses are prescription glasses focused at screen distance (about 20 to 26 inches), sometimes with multifocal lenses. The AAO says they may reduce strain for people at a computer for hours at a time. Ask your eye doctor.
- Blue light-blocking glasses: the AAO says there's no scientific evidence that blue light from devices damages the eye. It notes that several studies suggest these glasses don't improve eye-strain symptoms, and it does not recommend any special blue light-blocking eyewear for computer use.
Where blue light does matter: sleep
The AAO says blue light affects your circadian rhythm, and too much at night can make it harder to fall asleep. Its suggestions are to limit screens in the two to three hours before bed and to use nighttime settings on your devices in the evening. It also notes that the sun is a far bigger source of blue light than screens.
Contact lens wearers
The AAO suggests giving your eyes a break by wearing glasses instead on long screen days. It also says never to sleep in contact lenses, even "extended wear" ones, and to follow good lens-cleaning practices.