RESEARCH SHOWS THAT DETERIORATING EYESIGHT and repetitive motion disorders (RMD) such as carpal tunnel disorder may be two unwanted side effects of computer popularization. Three things to think about when installing computers in schools are viewing distance and angle from the computer monitor, chair design and height, and room lighting and ventilation.

A number of studies have been done regarding the most suitable maximum and minimum distances from the monitor. The results ranged from about 16 to 24 inches for minimum viewing distance, and from 28 to 37 inches for maximum viewing distance. In actual practice, a viewing distance range between 20 and 28 inches from the computer monitor would probably be suitable for most situations. In order to achieve this it would be useful for instructors to note the average student's position in front of the screen and then adjust the location of the monitor on the desk accordingly.

When facing the computer monitor the line of vision from the students' eyes should be about parallel with the top of the monitor screen. They should be looking at a slightly downward angle. This position can be achieved by all users with the provision of an adjustable height chair, which is highly recommended for all computer stations. A filter over the monitor screen to reduce glare is also suggested if glare cannot be eliminated by re-arrangement of lighting or furniture. 

In the US the most prevalent RMD is carpal tunnel disorder, caused by excessive compression of the median nerve in the wrist and which affects up to 3% of all VDT users. To avoid excessive wrist compression when typing, the keyboard should be on a plane parallel to or slightly below the level of the elbows, and inclined enough to allow the user to hold his or her wrists comfortably. It should also be placed deep enough on the desk to allow support for wrists and forearms. An adjustable height chair allows users to achieve this proper arm position along with the proper eye level at the top of the monitor.

It has been noted that the best position for computer use is an erect posture, which includes feet flat on floor or supporting surface. If most students’ feet cannot reach the floor when their chairs are adjusted to the correct angle for vision and arms, then either the computer desk should be lowered or foot stools provided.

Glare on monitor screens can cause eye fatigue, strain, headaches and loss of concentration. To reduce glare it is recommended that rooms which are devoted to computer use be windowless or equipped with curtains or screens that can completely block out or control outside light. Indirect, wide dispersion lighting (bounced from ceiling and walls) has been found to be effective in eliminating screen glare. If overhead fluorescent lights are used they should be on a line parallel to the user’s line of sight to the computer screen and to one side rather than directly above the user, and equipped with fixtures to direct light downward. When these conditions cannot be met or if glare persists, glare-reducing filters can be used as an effective substitute, though they may reduce readability.

Because computers and peripherals generate heat, rooms which have no windows or in which screens are used to close the room off naturally tend to become overheated. Computer rooms therefore require air conditioning and ventilation systems that can offset this overheating effect. If windows are uncovered to provide ventilation or extra lighting, they should be to the user’s side rather than in front or behind. Mesh blinds can provide light control while still allowing air flow and outside view.

 
For more detailed information on the ergonomics of learning please refer to the following sources:

Ergonomics and the Learning Environment by G.F. McVey (McVey, 1996)
The Computer User's Survival Guide by Joan Stigliani (Stigliani, 1995)

John Comerford, Graduate Student
SDSU Educational Technology

Comerford, J. (2003). Ergonomics in the computer classroom. In B. Hoffman (Ed.), Encyclopedia of Educational Technology.