eyes

READ - ENTER - CONTROL

These are the three most important steps we continuously perform in our computer-based jobs, without realizing properly. Our eyes continue to follow the commands from our brain, our attention is strongly focused, sometimes we are staring fascinatedly onto the monitor not to miss anything and to be able to undo small mistakes immediately. 

Are there warning signals for strain of the eyes?

Here, there is a difference between visually asthenopic and ocularly asthenopic complaints. Visually asthenopic complaints are subjective impairments of vision, such as interim shortsightedness, double vision, changes in color, smarting, watering, read eyes, flickering images, tic of the eyelids.

Ocularly astehopic complaints, in contrast, are subjective impairments of the eye, such as smarting, stabbing or redness. Additional warning signals for a strain of the eyes are fatigue, exhaustion and headache, especially in the forehead.

What can be done against it?

Give your eyes a break from time to time, try to relax by focusing a point far, far away - not only with your eyes, also with your mind!
Close your eyes once in a while to give the surface of your eyes - your corneas - sufficient humidity. Especially due to your increased attention you decrease your blinking frequency - the wettening of your eyes by blinking - when you are working at a monitor, so that the ocular surface will become too dry. The result is more or less severe smarting.
Whenever possible, take an outdoor break to gather new energy
Try to do a little exercise in your free time.

Are there any legal regulations?

According to the German regulations for monitor work (Bildschirmarbeitsverordnung), effective as of Dec. 20, 1996, employees have the right to have their eyes and vision examined with the eye test G37. The relevant European guideline transferred into national law with this regulation is 90/270/EEC on monitor work-stations.

Which tests are included in the eye test according to G37?

By screening it is possible to detect abnormalities or deviations in the users´ vision and to recommend a visual aid or ophthalmological control, where required. The costs of such examinations according to section 9, para 1 90/270/EEC are to be born by the employer. The costs for an ophthalmological eye test according to section 9, para 2 90/270/EEC as well as for potentially needed standard visual aid are refunded by the health insurances. Experience shows that a partial dereflection of the glasses used in monitor work is recommendable, since the share of scattered light is reduced and the visual perception is improved. However, the costs for dereflection are to be paid by the user.

The eye test includes the following examinations:

The individual examinations will be briefly explained in the following.

Examination of the visual acuity

The visual acuity is the capability of the eye to realize two separate points. The normal visual acuity cannot be fully used if abnomalies, such as far- or short-sightedness exist. For this reason, it is important to know whether the visual acuity must be corrected for the typical visual distance in monitor work "eye - monitor". Firstly, a further deterioration of vision should be prevented, and secondly, the strain for the eyes in monitor work should be reduced to improve the wellness of the user. As of the 40th year, the acuity of near vision considerably decreases. Therefore it is important to go to the scheduled control examinations. If there are no complaints, employees over 40 years should have an eye examination every 3 years, employees under 40 every 5 years.

far-/near-vision

Continuous accomodation (adjustment of the eye to different distances) may lead to tired eyes and headache. Continuous accomodation results from

Position of the eyes

Phorias (malposition of the eyes) are relatively frequent findings in this kind of examination. Here, vertical deviations are tolerated less than horizontal ones. Malpositions of the eyes are of special importance in monitor works requiring high precision and targeting.
In this part of the test, two filters of different colors (or dichromatic spectacles, respectively) are used to verify whether a colored geometrical body (e.g. a small circle) can be detected inside a larger body of different color (e.g. large circle).

Color vision and spatial vision

All above visual deficiencies can be corrected. If color vision is impaired, which is true for about 8 % of the male and 0.2 % of the female population, no improvement can be achieved by prescription of a visual aid. Therefore, software designs must also take colors into account. As the major part of the patients concerned suffer from a red-green weakness, for example, red or red underlayed error reports should contain an additional, definite identification characteristic. In addition, with an existing red-green weakness the otherwise three-dimensional space appears two-dimensional.
The possibility of individual screen designs supports the perception of screen information in this visual deficiency. The user should have the option to select colors as well as degrees of brightness.
To control the perception of spatial depth (spatial vision), different visual signs (two bodies at different distances) are shown in a test device or test picture with increasing stereoscopic requirements.

Central visual field

The examination of the central visual field is designed to detect retinal diseases within the area of highest resolution. In the peripheral zones of the visual field, there is only black and white perception, from the periphery to the center yellow, blue and more centrally red-green perception follow. Fluent reading of a text can only be guaranteed if the eye is able to still perceive symbols within a visual angle of about 2 degrees clearly and definitely. In the peripheral areas, in contrast, the visual acuity decreases.

Functional vision and still complaints during work at a monitor: Why?

If there are no findings in the eye test to be performed - according to the European monitor guideline - in a person with the appropriate qualification (i.e. no impairments are diagnosed), it is assumed that, under optimal conditions (hardware, utensils, work environment, software) the monitor user will be able to work at a monitor for a longer period of time without complaints. If work-related complaints should originate disregarding the test result, the conditions at work and the behavior of the user at the work-station should be investigated.
In addition to unergonomic conditions at the monitor work-station in terms of equipment of the work-station (hardware, furniture, environment, software), the user him- or herself often does little to support his or her health. The reasons are:

The sensitization of the employees regarding the potential consequences of monitor work and the information on the due use of the equipment (installation, setting) and an ergonomic behavior contribute to a user-optimized monitor work. Often, the employees behave "unergonomically" out of a lack of knowledge and in this way cause self-made stress, e.g. due to lack in exercise, unergonomic position, wrong adjustment of the monitor etc.

Which characteristics should the work-station have?

What are the common ergonomic guidelines?

CE-Standard: European standard for electromagnetic compatibility.

TÜV/GS:  German mark for proved safety.

TÜV Ergo: German mark for proved ergonomics. 

ISO 9241-3: International ergonomics standard for displays.

MPR II: Predecessor (today subunit) of the TCO standard. Standard for low-frequency magnetic, electric fields and electrostatic potential in monitors. However, does not contain power management. 

TCO ´92: Schwedish standard for monitors defining narrowest limits for electromagnetic fields and energy-saving measures (power management).

TCO ´95: Schwedish standard for monitors, containing the TCO ´92 and dealing with ergonomic quality, emissions, energy-saving and ecological aspects of a product, in addition.

Energy Star (EPA): US standard for decreasing power consumption.

Nutek: Standard for three-step energy-saving function of monitors.

VESA DPMS: Standardized method to approach the energy-saving function in 4 steps. 

Should the eyes be protected with tinted glasses?

No, these glasses are rather disanvantageous when working at a monitor. They are not suitable, since they change the brightness unfavorably. Dereflection is a different story, because dereflection reduces the reflexes originating on the glass.

If you have only one eye with a good visual acuity - can you work at a monitor?

Yes, however, due to the missing binocular vision intermediate recreation breaks should be made when required.

More about the German monitor work-station regulations, legal wordings ... under SANUS. SANUS is a joint project of several universities and companies dealing with software development and consultation.