• Who will be using the computer? – If the computer will only be used by one person then the arrangement can be optimized for that person’s size and shape, and features such as an adjustable height chair may be unnecessary. If it’s going to be used by several people, you will need to create an arrangement that most closely satisfies the needs of the extremes, that is the smallest and tallest, thinnest and broadest persons, as well as those in between these extremes.
• How long will people be using the computer? If it’s a few minutes a day then ergonomic issues may not be a high priority. If it’s more than 1 hour per day it is advisable that you create an ergonomic arrangement. If it’s more than 4 hours then you should immediately implement an ergonomic arrangement.

• Desktops – most ergonomic guidelines for computer workstation arrangements assume that you will be using a desktop system where the computer screen is separate from the keyboard.
• Laptop computers are growing in popularity and are great for short periods of computer work. Guidelines for laptop use are more difficult because laptop design inherently is problematic – when the screen is at a comfortable height and distance the keyboard isn’t and vice versa. For sustained use you should consider purchasing either:
• an external monitor
• an external keyboard
• laptop riser

Chair armrests – Having armrests on a chair can be helpful to aid getting into and getting out of the chair. Also, the armrests can be useful for the occasional resting of the arms (e.g., when on the phone, sitting back relaxing). However, it is not a good idea to permanently wrest the forearms on armrests while you are typing or mousing because this can compress the flexor muscles and some armrest can also compress the ulnar never at the elbow. Ideally, it should be easy to get the armrests out of the way when you need to have free access to the keyboard and mouse. These days most office chairs have armrests and many of them have adjustable height armrests, so look for a chair that is a comfortable fit to you and that has broader, flatter, padded armrests that you can easily move out of the way if needed is the best approach. If you are able to occasionally rest your hands on the keyboard on a palm rest and if you have a comfortable chair that does not have any armrests then this is also quite acceptable.

• Word processing – arranging the best keyboard/mouse position is high priority.
• Surfing the net, graphic design – arranging the best mouse position is high priority.
• Data entry– arranging the best numeric keypad/keyboard is a high priority.
• Games – arranging the best keyboard/mouse/game pad is a high priority.

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″ below the top of the monitor casing (not the screen). Sit back in your chair at an angle of around 100-110 degrees (i.e., slight recline) and hold your right arm out horizontally, your middle finger should almost touch the center of the screen. From that starting position you can then make minor changes to screen height and angle to suit. Research shows the center of the monitor should be about 17-18 degrees below horizontal for optimal viewing, and this is where it will be if you follow the simple arm extension/finger pointing tip. You 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, you will crane their neck forwards, if it’s too high you’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 sit 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.
• Biewing 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 40′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.
• Use a document holder that can be comfortably seen:
  • Use an in-line document holder that sits between the keyboard/keyboard tray and screen and is aligned with your body midline so that all you have to do is look down to see the documents and raise your eyes to see the screen.
  • Use a screen-mounted document holder and position this to the side of your screen that is your dominant eye
  • Use a freestanding document holder and position this next to the side of the screen and slightly angle it so that it follows a curve from the side of the screen.

• 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.

• Make sure that those things the user uses most frequently are placed closest to the user so that they can be conveniently and comfortably reached.
• Make sure that the user is centered on the alphanumeric keyboard. Most modern keyboards are asymmetrical in design (the alphanumeric keyboard is to the left and a numeric keypad to the right). If the outer edges of the keyboard are used as landmarks for centering the keyboard and monitor, the users hands will be deviated because the alphanumeric keys will be to the left of the user’s midline. Move the keyboard so that the center of the alphanumeric keys (the B key, is centered on the mid-line of the user).
• make sure that the phone is also close to you if you frequently use it.

A good workstation ergonomic arrangement will allow any computer user to work in a neutral, relaxed, ideal typing posture that will minimize the risk of developing any injury. An ideal keyboard arrangement is to place this on a height adjustable negative-tilt tray. An ideal mouse arrangement is for this to be on a flat surface that’s 1-2″ above the keyboard and moveable over the numeric keypad. If you want a surface at the level of the keyboard base then make sure that this can also be angled downwards slightly to help to keep your hands in wrist neutral while you are mousing, and keep your elbow is as close to the body as possible while you work.

• Lighting – make sure that the lighting isn’t too bright. You shouldn’t see any bright light glare on the computer screen. If you do, move the screen, lower the light level, use a good quality, glass anti-glare screen. Also make sure that the computer monitor screen isn’t backed to a bright window or facing a bright window so that there’s the screen looks washed out (use a shade or drapes to control window brightness).
• Ventilation – make sure that you use your computer somewhere that has adequate fresh-air ventilation and that has adequate heating or cooling so that you feel comfortable when you’re working.
• Noise – noise can cause stress and that tenses your muscles which can increase injury risks. Try to choose a quiet place for your workstation, and use low volume music, preferably light classical, to mask the hum of any fans or other sound sources.

• Eye breaks – looking at a computer screen for a while causes some changes in how the eyes work, causes you to blink less often, and exposes more of the eye surface to the air. Every 15 minutes you should briefly look away from the screen for a minute or two to a more distant scene, preferably something more that 20 feet away. This lets the muscles inside the eye relax. Also, blink your eyes rapidly for a few seconds. This refreshes the tear film and clears dust from the eye surface.
• Micro-breaks – most typing is done in bursts rather than continuously. Between these bursts of activity you should rest your hands in a relaxed, flat, straight posture. During a micro-break (< 2minutes) you can briefly stretch, stand up, move around, or do a different work task e.g. make a phone call). A micro-break isn’t necessarily a break from work, but it’s a break from the use of a particular set of muscles that’s doing most of the work (e.g., the finger flexors if you’re doing a lot of typing).
• Rest breaks – every 30 to 60 minutes you should take a brief rest break. During this break stand up, move around and do something else. Go and get a drink of water, soda, tea, coffee or whatever. This allows you to rest and exercise different muscles and you’ll feel less tired.
• Exercise breaks – there are many stretching and gentle exercises that you can do to help relieve muscle fatigue. You should do these every 1-2 hours.
• Ergonomic software – working at a computer can be hypnotic, and often you don’t realize how long you’ve been working and how much you’ve been typing and mousing. You can get excellent ergonomic software that you can install on your computer. The best software will run in the background and it will monitor how much you’ve been using the computer. It will prompt you to take a rest break at appropriate intervals, and it will suggest simple exercises.