In the last two decades, the computer has become unconditional accessory for everyone whether at the office, at home or even in the street. The democratization of this tool and the expansion of Internet usage, mean that users tend to spend more time face to computer, sometimes ignoring the risks that this could present to their health and especially the damage to eyes.


The computer screen is now a light source to which our eyes are confronted less dazzling than the sun, a lamp or other source of light, but powerful enough to harm if used without some precautions. If the screen does not destroy the vision, do not worry too much because he tired considerably eyes and irritates.


Like any other electronic device, computer monitors emit electromagnetic waves. Worse still, these radiations are directly perceived by the eye.


Despite the standards imposed on manufacturers of monitors thus limiting the risks, users must also comply with certain rules of use.


Direct effects of prolonged exposure :


Working on the computer requires a great visual attention, it cligne less eye therefore, 10 to 20 times per minute in normal and 2 to 5 times when it is before the computer screen, diminishing that blink the eye tends to dry out.


The positioning of the light facing the screen requires a more rigid than when reading a book or newspaper, which causes a more rapid evaporation of tears. The dryness of the eyes causes tingling and redness.


The work environment also plays an important role, a warm, dry air, dust or smoke, may also exacerbate the damage to the eyes.


The positioning of the screen and brightness of the office are also very important reflections on the surface of the screen cause eyestrain important. It must also avoid excessive brightness contrast between the screen and light sources around.


Screen CRT or TFT?



The cathode screens are still the most popular on the market, had begun to see normalize emissions and radiation at a distance of 50 cm (1.64041995 feet), a distance rarely respected by users. Despite these standards and constraints, they continue to present a big risk to the eyes.


Another major risk from the use of CRT is the presence of a high voltage transformer (THT), which increases the risk of prolonged exposure to electromagnetic fields. The screens currently used cathode emit radiation of a rate below international standards.


A flat screen consumes less power of course, it emits less radiation and a magnetic field much smaller and much less radiation, the flat surface of the screen also reduces glare which much less fatigue eyes.


The LCD or TFT, are not free of wrongdoing on the eyes. Besides the importance of pitch (the distance between the three elements of phosphorus, red, green and blue) that is bigger on LCD and TFT screens compared to CRTs. They also have a big problem response time even more fatigue to the eyes. The boundaries of the viewing angle is also an element of discomfort and limited freedom to move.


Equally important, refresh rate of the display screen LCD / TFT twinkle little they react more slowly than CRTs, increasing the refresh rate does not reduce eye strain significantly.


Some tips to see more clearly :



To begin with a visit to the optometrist cyclical needed, he mentioned that you work regularly on screen and redo a review after two to three years to see if your capabilities are maintained. Visual weaknesses must be corrected immediately, the work in front of a screen could be even more challenging.


There are also means to minimize the maximum inconvenience for the use of screens by following certain rules of proper use.


  • Avoid the reflection of light directly on the screen, which dazzles and limit readability.
  • Do not place the screen against a light source (back to the window), the difference in brightness fatigue considerably ocular muscles that are forced to continually adapt to different intensities of two light sources.
  • Avoid working in a very enlightened piece.
  • Reduce possible ambient lighting and have a desk lamp to illuminate the documents that must be read alongside the computer.
  • The positioning of the screen is important for eye comfort. The angle of vision must be about 30 degrees down (eyes at the edge of the screen). Away as possible while ensuring that it remains visible (50 to 80 cm).
  • Reduce the brightness of the screen if you can.
  • Increase the maximum refresh rate of 75Hz to a minimum.
  • Dust removal-screen regularly helps to better read and limit glare.
  • The eyes suffer from the air too dry, make sure to keep humidity reasonable (around 40% moisture).
  • Toggle-between work on the screen and other tasks (reading mail, documents, writing, chatting on the phone, etc.)..
  • Make several short breaks, stop 5 minutes every 30 minutes, it is preferable to long pauses infrequent.