How to reduce eye strain from screens
Digital eye strain is mostly a muscular and tear-film problem, not a light-damage problem. That changes which fixes are worth your time.
Match your screen to your room
The most common cause of strain is a screen much brighter than its surroundings, so your pupils cannot settle. Hold a sheet of white paper next to a white document on screen. If the screen glows noticeably brighter than the paper, turn it down. If the screen looks grey and dull next to the paper, turn it up.
This also means a screen that is comfortable at midday will be too bright at night. Adjusting brightness twice a day, or letting the system do it, removes a large fraction of evening strain.
The blink problem
Blink rate drops sharply during focused screen work — by more than half in some measurements. Fewer blinks means a thinner tear film, and that is what produces the gritty, burning, tired feeling. This is also why the symptoms clear within minutes of looking away.
The 20-20-20 habit is the standard advice for a reason: every twenty minutes, look at something about twenty feet away for twenty seconds. The distance relaxes the focusing muscle and the pause restores blinking. Set a timer if you will not remember.
Position and distance
Put the screen an arm's length away, with the top of the display at or just below eye level so your gaze is angled slightly downward. Looking down means less of the eye surface is exposed, which slows tear evaporation. A screen mounted too high is a common and easily fixed cause of dry eyes.
Contrast and text size
Small, low-contrast text forces continuous refocusing. Increasing text size by a step and using solid black-on-white or white-on-black rather than grey-on-grey costs nothing and reduces effort measurably. Dark mode helps some people considerably at night and makes text noticeably harder for others, particularly anyone with astigmatism — try both rather than assuming.
Flicker
If you get headaches from one screen but not another at the same brightness, backlight PWM dimming may be the difference. Raising brightness and lowering contrast in software often eliminates it, since PWM flicker is worst at low brightness.
Blue light filters, honestly
The evidence that blue light from screens damages eyes at these intensities is weak, and controlled trials of blue-blocking lenses have generally not shown a meaningful reduction in eye strain. What does hold up better is the effect of bright light in the evening on sleep timing — and for that, reducing overall brightness at night matters more than filtering one part of the spectrum. A warmer, dimmer screen after dark is worth doing. Expecting a blue light filter to fix strain caused by a too-bright screen at arm's length is not.
When to see someone
Persistent strain despite these adjustments often turns out to be an uncorrected prescription, an outdated one, or a convergence problem — all of which a proper eye examination will find. Screen work does not cause those; it just makes them impossible to ignore.