Computer Vision Syndrome

Computer vision syndrome (digital eye strain) is a group of eye and vision related problems resulting from prolonged use of computers, tablets, phones and other digital screens. It affects 50 to 90 percent of people who use screens for 2 hours or more a day. It is caused by the visual demands of screen work exceeding the visual system's capacity, and it is not known to cause permanent eye damage.

• Reduced blink rate while looking at a screen (about 5 to 7 blinks per minute compared with 15 to 20 normally), with more incomplete blinks, leading to tear evaporation and dry eye.
• Sustained accommodation and convergence at short working distances, with fatigue.
• Uncorrected or poorly corrected refractive error, presbyopia, binocular vision anomalies.
• Poor ergonomics: screen too high or too close, glare, reflections, flicker, contrast, small text, poor posture.
• Environmental factors: air conditioning, low humidity, smoke.
• Evidence that blue light filtering lenses prevent symptoms is limited. Digital device use in children is associated with myopia progression and dry eye.

• Eye strain, burning, dryness, watering, blurred vision at near or distance after screen use, double vision, headache, light sensitivity, neck, shoulder and back pain, difficulty refocusing, red eyes, sleep disturbance from late evening screen use.
• Examination: dry eye signs (reduced tear break up time, punctate staining), refractive error, accommodation or convergence problems, posture.
• Red flags: persistent headaches with visual loss or vomiting, double vision, eye pain with redness, field defects, drooping lid, recurrent headaches in children, very frequent blinking or squinting in children (consider refractive error or tics).

• Clinical, by symptoms linked to screen use and a workplace assessment.
• Full eye examination: refraction, accommodation, convergence, tear film (tear break up time, Schirmer test), ocular surface, and the Computer Vision Syndrome Questionnaire or Ocular Surface Disease Index.
• Examination of the working environment (distance, height, lighting, glare, font size).
• Differentials: uncorrected refractive error, presbyopia, dry eye disease, blepharitis, convergence insufficiency, migraine, tension headache, glaucoma, thyroid eye disease.

• Correct vision: full refraction with computer glasses where needed (single vision at the working distance, or occupational progressive or office lenses with intermediate and near zones for presbyopes); anti-reflective coating.
• Work habits: 20-20-20 rule (every 20 minutes look at an object 20 feet or 6 metres away for 20 seconds); 5 to 10 minute break every hour; conscious full blinking; do not work in the dark.
• Ergonomics: screen 50 to 70 cm away and 15 to 20 degrees below eye level; matte screen or anti-glare filter; reduce reflections from windows and lights; use the larger text size; adjust brightness and contrast; keep reference material at screen level.
• Dry eye: preservative free lubricants 4 to 6 times daily, warm compress and lid hygiene, humidifier, avoid air blowing on the eyes, drink adequate fluids, omega 3 fatty acids 1 to 2 g daily; ciclosporin 0.05 percent twice daily for persistent disease.
• Binocular vision problems: orthoptic exercises; prism glasses for selected cases.
• Children and teenagers: limit recreational screen time, outdoor time of at least 2 hours daily, break rules, regular eye examinations; avoid screens for an hour before sleep.
• Blue light filtering lenses and night mode may improve sleep comfort but have no proven effect on strain; they are optional.
• Review after 4 to 6 weeks; refer for persistent symptoms or red flags.