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title: "What screen eye strain actually is"
description: "Eye strain from screens has a clinical-sounding name and an unremarkable cause. The 20-20-20 rule is the most repeated piece of advice for it: every 2"
tags: ["post80"]
canonical_url: https://pause-paw.shop/blog/post80.html
Eye strain from screens has a clinical-sounding name and an unremarkable cause. The 20-20-20 rule is the most repeated piece of advice for it: every 20 minutes, look at something 20 feet away for 20 seconds. Most people hear it, try it for an afternoon, and have dropped it by Thursday. This covers what the rule actually does, where screen eye strain comes from in the first place, and how to get the reminder to survive a busy week.
What screen eye strain actually is
Screen eye strain, also called digital eye strain, is a cluster of symptoms rather than a diagnosis. Dry eyes, a dull ache behind them, blurred vision that clears when you blink, and a headache that shows up in the late afternoon. None of it damages the eye. That distinction matters, because the fear that screens slowly ruin your eyesight is not supported by the evidence, and believing it makes people skip the plain fixes that do work.
Two mechanisms produce most of the discomfort. The first is blink rate. People blink roughly 15 to 20 times a minute in conversation and about a third of that while reading a screen. Fewer blinks means the tear film breaks up and the surface of the eye dries out. The second is the focusing muscle. Holding focus at one fixed distance for hours keeps a single muscle contracted, and it gets sore the way any muscle held in one position gets sore.
How the 20-20-20 rule works
The rule addresses both mechanisms with one action. Looking at something about 20 feet away relaxes the focusing muscle, because at that distance it is close to rest. Holding it for 20 seconds gives the tear film time to spread back across the eye. The 20-minute interval is there because blink rate drops measurably within minutes of starting close work and stays down for the rest of the session.
20 feet is about six metres. In practice the far wall of most rooms is close enough, and a window is better. The distance does not have to be exact. What matters is that your eyes stop holding a near focus.
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