Screen time and eye strain

Two things happen at a screen. First, you blink about half as often as usual, so the tear film dries and the surface of the eye gets gritty and red. Second, the focusing muscle inside the eye holds one distance for hours without the natural resting glances at the horizon that reading a book or working with your hands gives you.

Add a small uncorrected power, a screen that is too close, too high or too bright, and text that is too small, and the eye is working hard all day. The result is the familiar evening: dry eyes, a dull headache, distance that takes a moment to sharpen when you look up.

The most useful lens for screen strain is simply the right power. A small astigmatism or a mild long sight that the eye copes with in daily life becomes a burden at a screen, and correcting it is often the single biggest relief. An anti glare coating cuts reflections from lights and the screen itself.

After forty, an ordinary reading pair is the wrong distance for a monitor, and a progressive lens gives only a narrow corridor for the screen. For people who spend most of the day at a desk, an office or computer lens made for the screen distance is worth asking about.

Blue cut lenses filter some of the blue light screens give off, and many wearers say long screen days feel easier through them. They are a reasonable choice for heavy screen users. They do not fix strain that comes from a wrong power, from not blinking, or from a screen set up badly, so we check those first and say so.

Children's eyes are still developing, and long hours of close work at a screen are linked with short sight increasing faster during the growing years. The same setup rules apply, with two more: time outdoors every day, which is protective, and a yearly eye test once a child wears spectacles.