Screen use, eye strain and what actually helps

Digital eye strain is genuinely common and genuinely uncomfortable, and almost everything sold to treat it addresses a mechanism that is not the cause.

What causes the symptoms

Two mechanisms, both well characterised.

Sustained accommodation: the focusing muscles work continuously at a fixed near distance, which produces fatigue in the same way that any sustained muscular effort does.

Reduced blinking: blink rate falls substantially during concentrated screen work, which destabilises the tear film and causes dryness, grittiness and intermittent blurring.

Add poor posture, glare, inadequate lighting and uncorrected refractive error, and the picture is complete.

None of these mechanisms involve permanent damage to the eye.

The blue light question

Where the evidence is clear and the marketing is not.

Screens do emit short-wavelength light, at intensities far below those shown to cause retinal damage in laboratory studies, and far below daylight.

Systematic reviews of blue-light-filtering spectacle lenses have not found evidence of benefit for eye strain symptoms, and have found little evidence for sleep or eye health benefits.

The effect of evening screen use on sleep is a separate and more defensible concern, and it is probably driven as much by content and timing as by light.

Which makes blue light lenses a poor use of money for eye strain specifically.

What does help

Free and effective.

Regular breaks from near focus — the commonly cited twenty-twenty-twenty rule, looking at something around twenty feet away for twenty seconds every twenty minutes, which is a rule of thumb rather than a validated protocol and which addresses the actual mechanism.

Deliberate blinking, and complete blinks rather than partial ones.

Lubricating drops for dryness, which are inexpensive and address the tear film directly.

Adjusting the environment: screen slightly below eye level, which reduces the exposed ocular surface; positioned to avoid reflections from windows and lights; ambient lighting that is neither dark nor glaring.

Increasing text size, since squinting is a common unnoticed contributor.

Adjusting screen brightness to match the surroundings.

And an up-to-date prescription, since uncorrected refractive error and early presbyopia produce exactly these symptoms and are frequently blamed on screens.

Presbyopia and the middle distance

A common cause of screen discomfort in people over about forty.

The ability to focus at near declines with age, and reading glasses set for reading distance are frequently wrong for a screen, which sits further away.

Which means that a dedicated intermediate-distance prescription, or occupational lenses designed for computer use, resolves symptoms that no amount of screen adjustment will.

Varifocals frequently require an unnatural head position for screen work, which produces neck pain attributed to posture.

Discussing your working distances specifically with the optometrist is the practical step, and it is rarely volunteered.

Dry eye

Which overlaps and has its own management.

Symptoms: grittiness, burning, fluctuating vision, and paradoxically watering, since reflex tearing responds to irritation.

Contributors include screen use, air conditioning, low humidity, contact lenses, some medications including antihistamines and antidepressants, and meibomian gland dysfunction.

Management: lubricating drops, preservative-free if used frequently; warm compresses and lid hygiene for gland dysfunction; humidifying the environment; and addressing contributing medications with a prescriber.

Persistent symptoms warrant an assessment rather than indefinite self-treatment.

Workstation setup

Which affects eyes, neck and back together.

Screen at arm's length, with the top of the screen at or slightly below eye level.

Document holder at the same distance and height as the screen if working from paper.

Chair supporting the lower back, feet flat, forearms roughly horizontal.

Position perpendicular to windows rather than facing or backing them.

And in many countries, employers have obligations regarding display screen equipment assessments and, in some, contributions towards eye tests and corrective appliances for screen work — which is worth knowing about and rarely claimed.

What warrants an examination

Rather than more screen adjustment.

Headaches associated with visual tasks.

Double vision.

Persistent blurring that does not clear on blinking.

Symptoms in one eye only.

Any sudden change.

And anyone who has not had an eye test in over two years, since the test detects considerably more than a prescription.

General information only, not medical advice. Consult an optometrist or qualified clinician about persistent eye symptoms or any sudden change in vision.