Glossary

Eye-health terms, in plain English

The words behind screen eye strain — what they actually mean, and where to read more. Quick, accurate, and cited in the linked guides.

Digital eye strain: The group of eye and vision symptoms — tired, dry, or aching eyes, blurred vision and headaches — caused by prolonged screen use.; Also called computer vision syndrome. It comes from long stretches of close focus, reduced blinking, glare and posture — not from any single cause.
Computer vision syndrome (CVS): The clinical name for eye and vision discomfort caused by extended computer, tablet or phone use.; CVS and digital eye strain describe the same set of symptoms. Studies put its prevalence among heavy screen users at roughly 69%.
Asthenopia: The medical term for eye fatigue — a tired, strained, aching feeling in and around the eyes.; A pooled analysis put asthenopia at around 51% of people, and linked it with neck and shoulder pain and short sleep.
Accommodation: The eye's ability to change focus between near and far by flexing the lens.; Holding focus at one close distance for hours tires the accommodative muscles, which is a big part of why screens leave your eyes feeling strained and slow to refocus.
Convergence insufficiency: A common near-vision problem where the eyes struggle to turn inward together to focus on close objects.; It can cause eyestrain, double or blurred vision and trouble reading. Guided convergence exercises have real clinical support — but a professional should confirm the diagnosis.
Tear film: The thin, multi-layer coating of tears that keeps the surface of your eye smooth, clear and comfortable.; Blinking spreads the tear film. Staring at a screen means fewer and less complete blinks, so the film breaks up and the eye dries out.
Dry eye: A gritty, burning or watery feeling that happens when the eye's surface isn't kept moist enough.; Screens are a common trigger because they cut your blink rate. Regular blinking, breaks and — if needed — lubricating drops help.
Blink rate: How often you blink — normally around 15–20 times a minute, but far less when focused on a screen.; Reduced, incomplete blinking during screen work destabilises the tear film and dries the eyes. Conscious full blinks help reset it.
20-20-20 rule: Every 20 minutes, look at something about 20 feet (6 m) away for at least 20 seconds.; A simple, evidence-supported habit that rests your focusing muscles and prompts a few full blinks during screen work.
Myopia (nearsightedness): A refractive error where distant objects look blurry because the eye focuses light in front of the retina.; In children it's linked to more near work and less time outdoors. Screens matter mostly because they mean more close focus and less outdoor time — not blue light.
Blue light: Short-wavelength visible light emitted by the sun and, in far smaller amounts, by screens.; Evidence that screen blue light damages the eyes is weak, and blue-blocking filters haven't been shown to prevent digital eye strain.
Glare: Harsh or reflected light that forces your eyes to work harder to see the screen clearly.; Reflections and mismatched brightness between the screen and the room are a common, fixable cause of screen eye strain.

Put the science to work

EyeReset turns this into gentle habits — the 20-20-20 rule and guided exercises, right on your iPhone.

Meet EyeReset