Body & HealthFact
At a screen you blink up to two-thirds less often.
Normally a person blinks about 15–20 times a minute. Staring at screens cuts that rate to a third to a half, so eyes dry out and sting. Add the constant strain of the ciliary muscle for near focus. Eye doctors recommend the 20-20-20 rule: every 20 minutes, look at something 20 feet (6 m) away for 20 seconds.
Useful: Blinking deliberately and looking out of the window is the cheapest eye care.
Source: pmc.ncbi.nlm.nih.gov