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Health condition · Clinically reviewed

Eyestrain, screens, sight tests and the 20-20-20 rule.

Tired, sore eyes and afternoon headaches after long stretches of near work. Common, uncomfortable, and almost always fixable with a sight test and some sensible changes.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against College of Optometrists, RCOphth and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including the 20-20-20 rule, workplace ergonomics and orthoptic assessment.

Key facts

Eyestrain at a glance.

The essentials, in plain English: what it is, what drives it, and how it is treated in the UK today.

  • What it is

    Asthenopia, also called digital eye strain or computer vision syndrome, a cluster of ocular and visual symptoms after sustained near work.

  • How common

    Very common. Around half of adults who use a screen for more than three hours a day report symptoms.

  • Main drivers

    Uncorrected refractive error, dry eye, prolonged screen use and reduced blinking, plus lighting and posture.

  • Not sight-damaging

    Eyestrain is uncomfortable and disruptive but does not cause permanent vision loss on its own.

  • First fix

    An up-to-date sight test and the 20-20-20 rule resolve most cases within a few weeks.

  • When to escalate

    Persistent symptoms, double vision or headaches warrant orthoptic or ophthalmology review.

Why this guide matters

A sight test first, gadgets a distant second.

Most eyestrain has ordinary causes. The three points below shape the rest of this page and, usually, the fix.

  • Refractive error is the usual culprit

    Uncorrected or undercorrected long-sight, short-sight, astigmatism and presbyopia drive most cases. An up-to-date sight test is step one.

  • Screens tire eyes, but they do not damage them

    Reduced blinking and sustained near focus cause temporary symptoms. Habits and setup, not new hardware, are what fix them.

  • Persistent symptoms deserve a specialist

    When symptoms outlast a sight test and sensible screen hygiene, orthoptic and ophthalmology assessment finds the reason.

How the diagnosis is made

From tired eyes to a clear plan.

The steps a UK optometrist, orthoptist or ophthalmologist will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    History and screen-time review

    A careful look at work patterns, hobbies, hours on screens, break habits, lighting and workstation setup.

  2. 02

    Assessing

    Symptom mapping

    When symptoms start, how long they last, and whether they resolve on rest or worsen through the day.

  3. 03

    Assessing

    Refraction and sight test

    A full optometric refraction to detect uncorrected or undercorrected myopia, hyperopia, astigmatism and presbyopia.

  4. 04

    Confirming

    Cover test and binocular vision

    Cover test, convergence near point and accommodative function to pick up muscle imbalance or convergence insufficiency.

  5. 05

    Confirming

    Slit lamp and dry eye workup

    Tear film assessment, meibomian gland review and staining to identify a dry eye contribution.

  6. 06

    Onward

    Orthoptic assessment

    Specialist orthoptic review for suspected convergence insufficiency or accommodative dysfunction.

  7. 07

    Onward

    Ophthalmology referral if needed

    For persistent or atypical cases, or when neurological features suggest migraine or another cause.

Typical timeline: sight test to settled plan in a few weeks.

Symptoms

What eyestrain actually feels like.

A familiar mix of ocular, visual and musculoskeletal symptoms that build with near work and ease with rest.

  • Sore, tired eyes

    A dull ache in and behind the eyes that builds through the day and eases with rest.

  • Burning and dryness

    Gritty, burning or itchy eyes from reduced blinking during focused screen work.

  • Blurred and double vision

    Intermittent blurring or occasional diplopia when shifting focus between near and far.

  • Headache

    Frontal or periorbital headaches, often building over an afternoon of near work.

  • Neck and shoulder pain

    Musculoskeletal ache from static posture at a poorly set up workstation.

  • Light sensitivity

    Discomfort in bright rooms or under overhead fluorescent lighting.

  • Difficulty focusing

    A lag when switching from screen to a document, or paradoxical watering of the eyes.

  • Red flag features

    Sudden vision loss, persistent double vision or severe unilateral headache need urgent assessment.

Treatment

How eyestrain is treated in the UK.

Correct the refraction, settle the ocular surface, sort out the workstation and, where needed, treat the underlying binocular vision problem.

  • 20-20-20 rule

    Every 20 minutes, look at something 20 feet away for 20 seconds. Simple, free and effective.

  • Correct refractive error

    Up-to-date glasses or contact lenses, including progressive lenses for presbyopia, remove a common driver of strain.

  • Workplace ergonomics

    Monitor at arm’s length with the top at eye level, neutral posture, and an Access to Work workplace assessment where appropriate.

  • Lighting and glare control

    Reduce glare, add anti-reflective coating to lenses, position task lighting to avoid reflections on the screen.

  • Treat dry eye

    Preservative-free lubricants, a humidifier, less air conditioning and blink exercises settle the ocular surface.

  • Screen settings

    Increase text size and contrast, use dark mode and warmer colour temperatures such as Night Shift in the evening.

  • Breaks, walking and posture

    Short movement breaks, hydration and posture resets protect both the eyes and the neck.

  • Vision therapy and orthoptics

    Specialist orthoptic exercises for convergence insufficiency and accommodative dysfunction, where indicated.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your optometrist, GP or ophthalmologist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • College of Optometrists. Guidance on digital eye strain and asthenopia.

  • Royal College of Ophthalmologists (RCOphth). Commissioning guidance and patient information.

  • NICE Clinical Knowledge Summaries. Dry eye disease.

  • American Academy of Ophthalmology. Computer vision syndrome patient information.

Red flags

When eyestrain is not just eyestrain.

Most cases are benign. These are the features that mean something else may be going on, and a specialist opinion is needed.

  • Sudden vision loss

    Any sudden loss of vision, in one or both eyes, needs same-day ophthalmology or emergency assessment.

  • Persistent double vision

    New or persistent diplopia may signal a neurological or ocular motor cause and needs urgent review.

  • Severe unilateral headache

    A severe one-sided headache with visual symptoms may indicate migraine, giant cell arteritis or another serious cause.

  • Flashes and floaters

    New flashes or a shower of floaters can signal retinal detachment and need same-day assessment.

  • Red, painful eye

    A red painful eye with reduced vision needs urgent ophthalmology review to exclude uveitis or angle closure.

  • Symptoms not settling after correction

    Ongoing strain after glasses correction and screen hygiene deserves an orthoptic opinion.

  • Migraine features

    Recurrent visual aura, throbbing headaches and nausea point towards migraine rather than pure eyestrain.

  • Neurological features

    Weakness, speech disturbance, unequal pupils or facial droop need emergency neurological assessment.

  • Children with persistent strain

    Children with persistent eyestrain deserve a full paediatric sight test to exclude amblyopia and squint.

Living with it

Small habits, big difference.

Four practical things that carry most of the load day to day: rhythm, setup, ocular surface care and knowing when to step up.

A quiet reminder

Rest is a treatment, not a luxury.

Regular breaks away from the screen are not slacking. They are the most evidence-based intervention on this page.

  1. 01 Rhythm

    Build the 20-20-20 rule in

    Set a repeating timer on your desk or phone. Two minutes of far-focus every twenty is enough to reset near-focus fatigue.

  2. 02 Setup

    Fix the workstation once

    Monitor at arm’s length, top at eye level, chair supporting the lower back. A single afternoon of setup pays back for years.

  3. 03 Surface

    Keep the ocular surface happy

    Preservative-free lubricants at your desk, a small humidifier if the room is dry, and conscious blinks during long reads.

  4. 04 Escalate

    Don’t settle for headaches

    If symptoms carry on after a proper sight test and screen hygiene, ask about orthoptic assessment.

Frequently asked

Everything we get asked about eyestrain.

Quick answers on screens, blue light glasses, dry eye overlap and when to escalate.

  • What is eyestrain?

    Eyestrain, or asthenopia, is a cluster of symptoms after sustained near work. It includes tired, sore or burning eyes, blurred or double vision, headache and neck ache. Digital eye strain and computer vision syndrome are the same condition described in the context of screens.

  • Does staring at screens damage my eyes?

    No. Screens do not cause permanent damage on their own. They do reduce your blink rate and encourage sustained near focus, which produces temporary symptoms. Correcting refractive error, treating dry eye and using the 20-20-20 rule usually resolves the issue.

  • Do blue light glasses work?

    Evidence is mixed. Most robust trials show little or no benefit for eye strain from filtering blue light. Well-fitting, up-to-date prescription glasses with anti-reflective coating help far more. Warm colour temperature in the evening may aid sleep, which is a separate benefit.

  • How do I know if it is dry eye rather than eyestrain?

    The two overlap. Dry eye tends to feel gritty and burning and is worse in dry, air-conditioned rooms. Eyestrain is more about tired, aching eyes and headache after near work. An optometrist can assess both in the same visit.

  • Should my child have their eyes tested for eyestrain?

    Yes. Children with persistent eyestrain, headaches or reading difficulty should have a full sight test. Uncorrected long-sightedness and convergence insufficiency are common and very treatable in this age group.

  • When should I see a specialist rather than an optometrist?

    If symptoms persist after up-to-date glasses and good screen hygiene, or if there is double vision, severe headache or any of the red flag features on this page, ask for orthoptic or ophthalmology review.

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