Workstation Ergonomic Tips: Computer Monitors and Posture
6. What can you see?
Make sure that any paper documents that you are reading are placed as close to the computer monitor as possible and that these are at a similar angle - use a document holder where possible.
The computer monitor should be placed:
- Directly in front of you and facing you, not angled to the left or right. This helps to eliminate too much neck twisting. Also, whatever the user is working with, encourage him/her to use the screen scroll bars to ensure that what is being viewed most is in the center of the monitor rather than at the top or bottom of the screen.
- Center the monitor on the user so that the body and/or neck isn't twisted when looking at the screen. However, if you are working with a large monitor and spend most of your time working with software like MSWord, which defaults to creating left aligned new pages, and you don't want to have to drag these to more central locations, try aligning yourself to a point about 1/3rd of the distance across the monitor from the left side.
- Put the monitor at a comfortable height that doesn't make the user tilt their head up to see it or bend their neck down to see it. When you are seated comfortably, a user's eyes should be in line with a point on the screen about 2-3 inches below the top of the monitor casing. We actually see more visual field below the horizon than above this (look down a corridor and you'll see more of the floor than the ceiling), so at this position the user should comfortably be able to see more of the screen. If the monitor is too low, the user will crane their neck forwards, if it's too high they'll tilt their head backwards and end up with neck/shoulder pain.
- Bifocals and progressive lens - even if you wear bifocals or progressive lens, if you sit back in your chair in a reclined posture (with you back at around 110 degrees) that is recommended for good low back health, rather than sitting erect at 90 degrees, and if you slightly tilt the monitor backwards and place this at a comfortable height you should be able to see the screen without tilting your head back or craning your neck forwards. Postural problems with bifocals can occur if you sits erect or even hunched forwards. The problem with low monitors is that they cause neck flexion and suffer more from glare. Recent studies have shown that the best position for a computer monitor is for the center of the screen to be at around 17.5 degrees below eye level. Try to align your eyes with the top of the viewing area of the screen, and this should put the center about right geometrically.
- Viewing distance - the monitor should be at a comfortable horizontal distance for viewing, which usually is around an arms length (sit back in your chair and raise your arm and your fingers should touch the screen). At this distance you should be able to see the viewing area of the monitor without making head movements. If text looks too small then either use a larger font or magnify the screen image in the software rather than sitting closer to the monitor.
- Screen quality - use a good quality computer screen. Make sure that the text characters on your screen look sharp, and that they are a comfortable size (you can change the screen resolution to find a comfortable and clear character size). If you can see the screen flickering out of the corner of your eye you should try increasing the refresh rate of your monitor (with a PC you can change monitor resolution and refresh rates using the Monitor control panel in your Settings folder, with a Mac you can use the Monitor control panel). You can also consider using a good quality glass anti-glare filter or an LCD display (like a laptop screen).
- Eye checkup - there are natural changes in vision that occur in most people during their early 50's. It's a good idea to periodically have your eyes checked by a qualified professional. If any screen adjustments feel uncomfortable then change them until the arrangement feels more comfortable or seek further professional help.
7. Posture, posture posture!
Good posture is the basis of good workstation ergonomics. Good posture is the best way to avoid a computer-related injury. To ensure good user posture:
Watch the user's posture!
- Make sure that the user can reach the keyboard keys with their wrists as flat as possible (not bent up or down) and straight (not bent left or right).
- Make sure that the user's elbow angle (the angle between the inner surface of the upper arm and the forearm) is at or greater than 90 degrees to avoid nerve compression at the elbow.
- Make sure that the upper arm and elbow are as close to the body and as relaxed as possible for mouse use - avoid overreaching. Also make sure that the wrist is as straight as possible when the mouse is being used.
- Make sure the user sits back in the chair and has good back support. Also check that the feet can be placed flat on the floor or on a footrest.
- Make sure the head and neck are as straight as possible.
- Make sure the posture feels relaxed for the user.