Eye Strain

Eye strain (asthenopia) is a group of symptoms caused by prolonged or demanding visual tasks, including aching, burning, tired or sore eyes, headache and sometimes blurred or double vision. It is very common and not harmful to the eye, but it reduces comfort and productivity. Symptoms usually settle with rest and correction of the cause.

• Uncorrected or under corrected refractive error (hyperopia, astigmatism, early presbyopia, myopia), wrong spectacles.
• Binocular vision problems: convergence insufficiency, accommodative dysfunction, heterophoria.
• Prolonged near work and screen use, reduced blink rate, dry eye.
• Environment: poor lighting, glare, flicker, incorrect screen distance or height, dry air, smoke.
• Systemic: sleep deprivation, migraine, sinus disease, anxiety, thyroid eye disease, medication effects.
• Rare serious causes: raised intracranial pressure, intermittent angle closure glaucoma, neurological disease, ocular inflammation.

• Tired, heavy, aching or burning eyes, brow or temple headache after reading or screen work, eye rubbing, blurred vision when changing focus, double vision at the end of the day, light sensitivity, watering or dryness, neck and shoulder pain.
• Symptoms ease with rest and recur with the activity.
• Examination: normal eyes at rest; visual acuity, cover test, near point of convergence, accommodative amplitude, tear film.
• Red flags: sudden or persistent double vision, headache with vomiting or visual obscurations, severe eye pain with redness or haloes, field loss, drooping eyelid, proptosis, pain on eye movement, new squint, headache waking from sleep, neurological symptoms.

• Clinical, by history of task, duration and symptoms.
• Full eye examination: visual acuity, cycloplegic or manifest refraction, assessment of binocular function (near point of convergence normally under 6 to 10 cm; positive fusional vergence), accommodation tests, tear film, fundus and intraocular pressure when indicated.
• Neuro ophthalmic assessment, imaging or blood tests only for red flags.
• Differentials: uncorrected refractive error, convergence insufficiency, dry eye, blepharitis, migraine, tension headache, sinusitis, angle closure glaucoma, thyroid eye disease, idiopathic intracranial hypertension.

• Correct refractive error and presbyopia with up-to-date spectacles or contact lenses.
• Break rule: every 20 minutes of near work look at something 20 feet (6 metres) away for 20 seconds; take a longer break each hour; blink fully and often.
• Ergonomics: screen 50 to 70 cm from the eyes, top of the screen at or just below eye level, text size about three times the smallest readable size, reduce glare and reflections, even room lighting, adequate task light, adjust screen brightness to match surroundings.
• Preservative free lubricant drops (carmellose 0.5 percent or sodium hyaluronate 0.1 to 0.4 percent) 4 to 6 times daily if dryness is present; humidify dry rooms.
• Convergence insufficiency: office based vergence therapy with home exercises (for example pencil push ups, 15 minutes daily 5 days a week for 12 weeks) is effective.
• Treat associated conditions: blepharitis (lid hygiene), migraine, allergy, sleep problems.
• Reading glasses with prisms are rarely needed.
• Review in 4 to 6 weeks; refer if symptoms persist despite correction or red flags are present.