Computer vision syndrome (CVS) — also called digital eye strain — affects an estimated 65% of regular screen users. Here's what it is, what causes it, how to recognise it, and how to treat it.
Definition
Computer vision syndrome is a group of eye and vision-related problems that result from prolonged use of digital screens — computers, tablets, phones, and e-readers. It was formally defined by the American Optometric Association and is now one of the most common workplace health complaints globally.
CVS is not a single condition but a cluster of symptoms that share a common cause: the visual demands of screen use exceed the comfortable capacity of the visual system over sustained periods.
Symptoms
→Eye strain and fatigue
→Headaches
→Blurred or double vision
→Dry or irritated eyes
→Burning or stinging eyes
→Watery eyes
→Neck and shoulder pain
→Difficulty refocusing
→Increased sensitivity to light
→Dizziness or nausea
What causes it
Reduced blink rate
Blink rate drops by up to 70% during screen use — from 15–20 blinks per minute to 3–5. Without regular blinking, the tear film that lubricates the eye surface breaks down, causing dryness, burning and irritation. This is the most significant and most overlooked cause of CVS.
Accommodative demand
Screens require sustained near-focus, keeping the ciliary muscle in continuous contraction. Over 20–30 minutes, this muscle fatigues, causing aching eyes, headaches and blurred vision.
Poor ergonomics
Screen distance too close, height too high or too low, and glare from lighting all compound visual effort and accelerate symptom onset.
Uncorrected vision
Even mild refractive errors — nearsightedness, farsightedness, astigmatism — are significantly amplified during screen use, as the visual system works harder to compensate.
Environmental factors
Air conditioning, heating, and low humidity accelerate tear evaporation, worsening the dry eye component of CVS.
How is it diagnosed?
CVS is primarily a clinical diagnosis based on symptoms and their correlation with screen use. An optician can assess blink rate, tear film stability, binocular function, and refractive error — all of which may contribute. A comprehensive eye exam rules out underlying conditions and identifies whether a prescription update or vision therapy might help.
Treatment and management
CVS has no single cure — it's managed through a combination of habit changes, ergonomic improvements, and where necessary, optical or medical interventions:
✓Regular breaks — the 20-20-20 rule as a minimum
✓Conscious blinking and blink rate monitoring
✓Correct screen distance (50–70cm) and height (top at or below eye level)
✓Lubricating eye drops for dry eye component
✓Updated prescription if refractive error is contributing
✓Improved workspace lighting — no glare, ambient brightness matched to screen
✓Humidifier in dry environments
✓Screen-free time before sleep
Does CVS cause permanent damage?
In most adults, CVS does not cause permanent eye damage. Symptoms are temporary and resolve with appropriate rest and habit changes. However, chronic dry eye — which can develop from sustained, unmanaged tear film disruption — is a progressive condition that warrants treatment. If symptoms are persistent despite habit changes, an optician visit is recommended.