Visual fatigue
Burning, itching, dryness, watering, red eyes, headache or blurred vision. It goes away with visual rest. When you stare at the screen you blink less and your eyes dry out. The INSST guide suggests:
- 20-20-20 rule: every 20 minutes, look at something about 6 metres (20 feet) away for 20 seconds.
- Alternate looking far and near for 10-15 seconds each, and blink often.
Posture and sitting too long
Sitting still for most of the day is linked to neck and back pain and to cardiovascular disease, type 2 diabetes and high blood pressure. The guide recommends short breaks, for example every 30 minutes, to stand up, walk and stretch.
Mental workload
This is the mental effort the work demands. Too much leads to fatigue and mistakes; too little, in monotonous tasks, to boredom and anxiety. That is why the assessment must look at mental workload together with eyesight and posture (article 3.2).
Source: INSST, Guía técnica de pantallas de visualización (technical guide on display screens, 2021, in Spanish), appendix 2, visual fatigue, physical problems and mental workload · Real Decreto 488/1997, sobre trabajos con equipos que incluyen pantallas de visualización (work with display screen equipment; consolidated text, in Spanish), article 3.2