Catalan Association of Optometry and Vision Therapy

Ergonomy and visual hygiene

The definition of health tells us about the "Part of medicine that is aimed at health maintenance and disease prevention." Therefore, visual hygiene standards are an easy set to follow, which aim to control the factors that may cause a harmful effect on vision.

Visual hygiene standards help improve visual problems, not solve them com

What is meant by ergonomics?

The word ergonomics comes from the Greek ergon= work and nomos: the study of

Ergonomics is the science that studies the relationships between human beings and the work done to bring together physiological conditions of the person and the technology of the machines used to perform their work.

Here are a few visual hygiene and ergonomic rules that are useful in different situations common in our daily life:

- For reading and writing
  1. Environment: to maintain the airy studio room and a normal temperature.

  2. Furniture: must be suitable for children.

    -Chair: adjustable in height.

    -Table: ideal to have an inclination of 20 degrees, so the posture is more relaxed, stress will be less visual and breathing easier. You can also use a lectern. Place the desk in front of a window or open space, never facing a wall.

  3. Posture: sit properly. The feet have to touch the floor; legs must be bent back at an angle and touch the back.

  4. Lighting: It is very important. We have an overhead light and one directly at the level of work, not directly into the eyes, removing glare and shadow. The table light should be positioned to the left for right-handed people and vice versa for left-handed. Work whenever possible with natural light and artificial lighting when the sun starts to go.

  5. Working distance: between the eyes and the paper must have at least the distance between the elbow and the tip of the index finger (30 to 40 cm). Do not work in a table too high, or read or write too close to the text.

  6. Time: every 30 min. study is to make a stop of 2 min. during which we have to look away, if possible through a window.

  7. Never turn or tilt the paper while reading or writing. A slope of more than 20 degrees will involve the removal of a functional eye.

  8. The forearms should be flat on a work surface and not move your head to read.

  9. The diet should be rich in vitamin A (milk, carrots, plums, egg yolks), vegetables and fruits.

  10. Field trips are recommended, free or open spaces.

- When i watch the tv and play videogames
- Distance: the optimum distance is at least 2 m.

- Lighting: always keep ambient light, no television in the dark. It must avoid glare and reflections on the screen.

- Posture: do not watch TV straight on the couch or in bed or with the head bent. All these positions prevent the information coming equally to both eyes.

- Time: Do not allow children to watch television more than two hours a day.

- Working with the computer

- Light colours and matte. Avoid reflections.
- Screen image: should be stable with no glare or reflections. Avoid eyestrain.
- Adjustable at will. Optimizes the viewing angle.
- Adjustable in terms of brightness and contrast. She has to adjust to environmental conditions. Optimize readability.
- Clean screen of dust and fingerprints. The electrostatic fields produced by cathode ray tubes attract dust affecting the airways and eyes.
- Place the screen at a distance between 50 and 60 cm never less than 40 cm. It must be located at a height similar to eye level or slightly lower. The best viewing area is between 5 ° and 35 °. The location must be perpendicular to the windows. Front and back window location causes glare causes and natural light reflections.
- Breaks: You should rest about 10 min. for each hour of work trying to look through a window or as far as possible.


- In front of the keyboard there must be enough space to rest the hands comfortably. Reduces fatigue in the arms and back.
- Directly below the monitor. Avoid side positions; this forces your head to turn.


There is no point having a team ergonomically prepared if then we work on a table where our legs don’t fit and/or sitting on backless chair.

- Chair: should be stable. Avoid involuntary displacement. Adjustable heights so your feet touch the ground, otherwise use a footrest. Back support mandatory.