What is CVS?Computer Vision Syndrome (CVS) is the general term used to describe a variety of vision-related symptons that may be caused or aggravated by regular use of a computer for two or more hours a day.
These symptons, which were identified by optometrists in a nationwide survey, include: temporary myopia (near sightedness),eyestrain headaches, blurred vision, dry or irritated eyes, neck and back aches, increased sensitivity to light, double vision and after-images.
The same survey uncovered four environmental factors that have the most impact on whether or not a computer user will develop CVS. These factors are:
|• the arrangement of the office:|
|• poor lighting|
|• screen resolution:|
|• screen glare|
|The Magnitude of the Problem
In 1991, James Sheedy, O.D., PhD., Chief of the VDT Eye Clinic at the University of California, Berkeley, conducted a nationwide survey of optometrists. Sponsored by the Optical Coating Laboratory Inc., manufacturer of GlareGuard® anti-glare filters, the survey sought to determine how many patients had eye problems caused by computer use, the most prevalent symptoms, diagnoses and treatment.
Respondents indicated that, on average 14.25 percent of their patients -- or nearly 10 million people annually - complain about symptoms primarily associated with computer use. The optometrists further reported that conventional treatment, such as prescription lenses or spectacle design changes, alleviated only a portion of the problem, the remaining symptoms being directly related to the computer work environment.
|Are you at risk for CVS?
To determine whether you are at risk for CVS, answer "yes" or "no" to the following statements:
|• The middle of the computer screen is about 20 degrees below eye level (opinion currently is 300 +/- 150.)|
|• If hard copy needs to be keyed into the computer, it is located about the same distance from the eye as the screen.|
|• Any windows are at right angles to the screen, rather than behind or in front of it.|
|• There is enough light to read hard copy without straining|
|• Screen reflections from overhead or desk lights are non existent.|
is adequate to produce sharply defined images on the screen.
|If you answered "no" to one or more of the above, you could be a candidate for computer vision syndrome. The greater the number of "no" responses, the more likely you are to develop CVS symptoms.|
|What can be done to minimise CVS?
Luckily , computer vision syndrome, once recognised, is fairly easy to correct. To begin, anyone who suspects CVS, or who works at a computer several hours a day, should have a thorough eye exam. Make sure your optometrist or ophthalmologist knows that you use a computer regularly. He or she may prescribe special glasses and/or a screen filter, as well as make other ergonomic recommendations.
If your doctor is not an ergonomics expert, you should consider making certain office modifications on your own. Review any "no" answers to the CVS risk assessment, above, and take steps to correct the situation.
|•||Try to place your computer at right angles to any windows. If this is not possible, put blinds on the windows or erect outside awnings to reduce direct sunlight.|
|•||Install a screen or partition behind the computer to reduce both outside light and overhead glare. Use non-reflective paint or coverings on the walls facing the computer.|
|•||Use equipment with brightness controls or add such controls to your screen. If possible, relocate lamps that cause reflections on the screen; add dimmer switches to overhead lights or use coverings on fluorescent lights. At the same time, make sure there is sufficient light to read hard copy without straining.|
|•||Adjust the height of your desk or chair so the middle of the computer screen is about 20 degrees below eye level. The screen itself should be 16-30inches from your eyes. Use a stand for hard copy so that the source documents and the computer screen are at roughly equal distance from the eyes.|
|•||Finally install an anti-glare, optically coated glass filter. Underscoring the value of this step, the American Optometric Association (AOA) recently granted its first Seal of Acceptance for any vision care product to GlareGuard. The high resolution, high contrast filter increases viewability dramatically -- a major contribution in the fight against CVS.|
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