Posture and Your Eyes
Vision is the most powerful determinant of your posture at work. It is impossible to maintain good postures throughout your workday, unless your work materials and equipment are thoughtfully placed within your line of sight and within your comfortable focus distance. In many cases, smart use of computer valets, copy holders, slant boards, and book stands have greater impact on your posture than a new ergonomic chair. Work surface height can also be very important.
Focus angle
Your body follows your eyes. To preserve proper posture, your visual target should be nearly parallel to your face and within your line of sight. Poor visual target position forces your spine to compensate by bending. This occurs when you try to sit in an erect posture to write on a flat surface.
Ideal reading angles are at about 60°, give or take. If you wear bifocals or if your upper back is rounded (e.g., kyphotic), your line of sight may be lower.
Ideal writing surface angles are somewhere between 10° and 20°. This is not ideal for vision and your spine, as both your neck and back will have to bend forward somewhat. However, writing at a steeper angle is likely to strain your shoulder and neck muscles. Artists and draftsmen often find ways to write or paint at steeper angles to protect their backs and necks. Generally, they do better if they can support their arms directly on the writing/painting surface as they work.
Focus distance
Each of us experiences our own best visual acuity at a certain distance.
Ideal focus distances for reading and writing average between 15" to 25" from the eyes. All of us are a little different. If your visual acuity point is at 16 inches, you will strain your body forward to focus on work that is more than 17 inches away.
Desk too low.
Desk at proper height.
Even without a desk angle,
posture is much improved.
Scope too far away.
Scope at proper distance from the eye.
Ideal focus distances for computer viewing is greater than for reading and writing. Research suggests there is less eye strain when your computer monitor at least 22" from your eyes. In the "old" days, just a few short years ago, computer monitor resolution was too poor to allow an ideal focus distance. Newer computer monitors with better resolution can be seen at greater distances, and the text can be made enlarged to make distant viewing easier. However, if you have a traditional box-style CRT, your desk is probably not deep enough to allow you to place it that far away from you. If this is your problem, consider a detached keyboard support -- or trade up your klunky old monitor for a new flat panel display -- or invest in a deeper desk. It's only money :-)
Older computer
monitors
had poor screen resolution
and were hard to see at
a healthy distance.
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