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(The Tribune - January 19, 2005)
Beware of computer vision syndrome
Dr Mahipal Sachdev
DO you spend more than two hours a day working on a computer? Do you sometimes experience headaches, loss of focus, burning/tired eyes, double or blurred vision or neck and shoulder pains? If the answer of any of the above questions is yes, then there are high chances are that you suffer from computer vision syndrome (CVS). CVS is a term used to describe eye strain and tiredness, temporary weak vision, dry irritated eyes, light sensitivity and other vision and muscular problems that stem from using a computer.
The causes
Visual problems: People who are already near-sighted, far-sighted, or have astigmatism are more likely to develop computer vision syndrome. Multi-focal lenses make it even more difficult because the screen is higher and further away from the zones meant for distance and near.
Computer glare and reflection: Glare from surrounding lamps and lights can also lead to eyestrain.
Improper workstation design: One of the most common problems in the workstation set-up is that the monitor of the computer is placed too high. The top of the screen should be at the eye level. This is because the ideal gaze angle is 10 to 20 degrees below the eye. A screen that is too high can lead to dry, irritated eyes as you blink less frequently. It also causes headaches and neck and upper back pain because the head is tilted back to see.
Dry environment and dehydration: These two very common occurrences in the workplace and home office can worsen the problem of irritated and dry eyes. The air quality is poor in many offices. To make matters worse, computer work can be very engrossing and you may forget to get something to drink. Or you may not feel you have the time to get up.
Reading new, unfamiliar material at work: When you strain to catch hold of unfamiliar information and have to do it on a tight deadline, the mind can become stressed and agitated. And when there is mental agitation or stress, this is transmitted to the whole upper body - the arms, shoulders, neck and head. This is why reading at work can be so draining and exhausting. But then you can go home and watch television for three hours or sink into your favourite chair with a magazine. Mental states can interfere with normal vision.
CVS is caused when the eyes and brain react differently to characters on the screen than they do to printed characters. Normally, eyes have little problem focusing on most printed material, which is characterized by dense black characters with well-defined edges.
Healthy eyes can easily maintain focus on the printed page. Characters on a computer screen, however, don’t have this contrast or well-defined edges. These characters (pixels) are brightest at the centre and diminish in intensity toward their edges. This makes it very difficult for our eyes to maintain focus and remain fixed onto these images. Instead, our eyes drift out to a point called the “resting point of accommodation” or RPA.This continuous flexing of the eyes focusing muscles creates fatigue and a feeling of tired eyes that are so common after long hours at the computer.
Nowadays, not only adults but also more and more children are using computers and for extended periods. Sitting for hours in front of a computer screen stresses a child’s eyes because the computer forces the child’s vision system to focus and strain a lot more than any other task. CVS not only affects the eyes but also leads to other kinds of aches and pain. Trying to avoid monitor glare often leads to improper posture which causes backache, neck-ache, etc. So, then, how can we avoid CVS, especially when a computer has become an essential part of our workplace and also at home?
Use proper lighting
Eyestrain is often caused by excessively bright light coming in from outside and excessively bright light inside. When you use a computer, the ambient lighting should be about half that used in most offices. Eliminate exterior light by closing drapes, shades, or blinds. Reduce interior lighting by using fewer light bulbs or fluorescent tubes, or use lower intensity bulbs and tubes. If possible, position your monitor so that windows are to the side of it, instead of in front or back.
Minimise glare
Glare on walls and finished surfaces as well as reflections on the computer screen itself can also cause eyestrain. You may want to install an anti-glare screen on your monitor. Again, when outside light cannot be reduced, use a computer hood. Have an anti-reflective coating applied to your glasses. This will prevent glare and reflections on the backside of your lenses from reaching your eyes.
Adjust the brightness of your computer screen
Closely match the brightness of the environment with that of your computer screen, by using the buttons on the monitor. Also adjust the monitor to make sure the contrast between the screen background and the on-screen characters is high. And make sure that the text size and colour are optimised for the most comfort. Also, position your desk lamp so that it doesn’t shine on the computer screen or into your eyes.
Blink more often
Blinking is very important when working at a computer — it rewets your eyes to avoid dryness and irritation. According to studies, people blink less frequently — about five times less than normally when working at a computer. Tears coating the eye evaporate more rapidly during long non-blinking phases and cause dry eyes. Office buildings may have excessively dry environment that also reduces tearing. Also try this exercise: every 30 minutes blink 10 times by closing your eyes as if falling asleep (very slowly).
Exercise and stretch your eyes
Look away from your computer screen every 30 minutes, and focus for 5-10 seconds on a distant object outside. Another exercise to readjust your focusing is to look far away at an object for 10-15 seconds and then near for 10-15 seconds, rocking your focusing back and forth between near and far. Do this 10 times. Both of these exercises will help you prevent strained near vision and stretch your focusing muscles.
Take frequent breaks
Follow 20-20-20 rule. Take a 20-second break and look 20 feet away every 20 minutes.
Modify your workstation
If you need to look back and forth between a printed page and your computer screen, this can cause eyestrain. Place written pages on a copy stand and adjacent to the monitor. Adjust your workstation and chair to the correct height. Purchase ergonomic furniture to insure proper screen locations and posture.
Exercise even when sitting
Anyone in a sedentary job, especially those using computers, should stand up, move about, or exercise their arms, legs, back, neck and shoulders frequently. While these measures will resolve the issue in many cases, it is recommended that the eye care practitioner be visited for consultation whenever symptoms of computer vision syndrome are observed.
The writer is Chairman and Medical Director, Centre of Sight, New Delhi
email: msachdev@bol.net.in
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