It is hardly surprising that the symptoms of computer vision syndrome are so prevalent. The eyestrain that is caused by sitting at a computer screen for hours on end viewing text and graphics, results in headaches and blurred vision and diminished work performance. Practicing visual ergonomics offers a commonsense approach to reducing eyestrain and improving poor basic work habits.

What exactly is visual ergonomics? Ergonomics is the study of human efficiency in a working environment. Visual ergonomics involves a more efficient interaction of your vision with the task you are performing on your computer, and learning how to minimize the strain on your eyes while you work.

Putting this concept into practise requires following some simple guidelines which will ensure you adopt sound work habits when using your computer. Looking at these guidelines, "twenty" seems to be the magic number which comes up time and again.

But it isn't just restricted to visual ergonomics. When designing an ergonomically-sound kitchen, for example, twenty feet is considered the maximum total distance between the work triangle of icebox, stove and kitchen sink.

Let's look in more detail at these simple rules. We are all familiar with the term 20/20 vision to denote perfect vision. But to keep our eyes healthy, and avoid the symptoms of computer vision syndrome, we should be following the 20/20/20 rule. Every 20 minutes or so, look away from your computer screen for at least 20 seconds at an object 20 feet away.

Why is this important? Studies have shown that constant near-point focusing on a computer monitor has contributed significantly to an increase in the number of cases of shortsightedness (myopia) among twenty to thirty-year-olds.

As babies we are born longsighted and our eyes are not fully developed until we are 8 years old. Living in a "near-point" world, and exposed to prolonged computer use from an early age which takes its toll on the undeveloped focusing muscles of young eyes, today's young adults are increasingly at risk from developing myopia.

Practicing visual ergonomics, therefore, helps protect young eyes, and monitoring software that reminds them when to stop is now available. Children are not as self-aware as adults, so regulating your child's time on the computer and encouraging him to follow the 20/20/20 rule is very important.

For those of us who are older and spend long periods in front of our monitors, it is an equally good idea to keep doing this exercise. As we age, our ability to do near work in comfort diminishes. This is because the eye's lens stiffens, compromising its ability to become rounded and so impairing our ability to see comfortably close up.

Focusing from near to far to a distance of 20 feet and back to near again several times a day can help slow down the hardening of the lens. This focusing and refocusing should form part of a general eye care program which should also include proper intake of vitamins and exercise. Visual ergonomics can, therefore, play a positive role not just in helping to counter the symptoms of computer vision syndrome, but also in keeping your eyes generally healthier.

If you have reached the "bifocal" age, and already wear bifocals or trifocals when using your computer, another twenty rule comes into play. Make sure your monitor is no nearer than 20 inches and, if you have a monitor larger than 20 inches, position it so that the top of the viewing area is approximately 3” above eye level. Lowering the monitor provides more comfortable viewing through your lower lenses.

Remember as well that, even with glasses, the computer screen can become blurred. Trying to read a fuzzy screen can cause a variety of vision-related aches and pains from a sore neck and shoulders to nagging back pain. When using a computer, your vision can adversely affect your body.

If you're struggling to read the screen through the lower portion of your bifocals, or through half-eye reading glasses, you tend to adopt a poor posture. Computer glasses, which enlarge the intermediate zone of your vision making text and graphics much easier to read, may be appropriate to assist you in achieving greater comfort at the monitor.

For some people the concept of visual ergonomics needs to be widened. Specific vision therapy programs, with the aim of improving binocular vision and efficient functioning of the visual system, have been developed for individuals suffering from ambylopia (lazy eye), strabismus (squint) and other eye alignment problems.

These programs offer vision training to get the eyes to work at their peak efficiency and alleviate eyestrain. Diagnostic testing, training procedures, along with the use of lenses and prisms, may all be involved in successfully treating these conditions. Tailored to the individual's specific binocular problem, the resulting improvements in how the eyes aim and focus together can lead to greater concentration and increased efficiency for near work.

Let's now go back to our work triangle in the kitchen and apply an important aspect of kitchen design to visual ergonomics in the office. The workplace in the 21st century differs markedly from the office of a few decades back. Then, typists did not have the modern work triangle of monitor, keyboard and copy, with its associated problems of eyestrain, to contend with.

A work triangle is necessary in the kitchen, but why in the office? By using a document holder, and keeping your hard copy close to the screen, you remove one side of the triangle altogether and create a more ergonomic angle. This immediately reduces eyestrain by reducing the number of times your eyes need to focus and refocus during the working day.

Here are three final tips for healthy computing. First, remember to blink fully and often to avoid dry eyes, a symptom of computer vision syndrome.

Second, to relax your eyes, cover them with your palms, take several deep breaths for 20 seconds, uncover your eyes and refocus. Repeat several times during the day.

Third, make sure you have an annual eye check-up. Take a note of your viewing distances, and give these figures to your doctor before the eye exam.

Don't forget, though, the most important figure in visual ergonomics is the number twenty. Follow the above guidelines and near vision tasks will become more rewarding and enjoyable.