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Vision
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For optimal vision health, periodic vision testing exams are recommended even if you have no current vision problems or discomfort. When you go for an exam, make sure you tell your eye care provider you use a VDT. This wil help the doctor prescribe the most appropriate course of action for your situation.
Eye discomfort is the most common health complaint associated with computer work . Typical complaints include: itchy, tired, dry and/or sore eyes.
Itchy eyes may be caused by dry air and/or allergic reactions. Dry winter weather is commonly associated with itchy eyes. At other times of the year, allergic reactions can aggravate this problem. During an allergy attack, your eyes tear, further increasing the itchy sensations.
Dry eyes may be aggravated by the fact that VDT workers tend to blink less due to the increased concentration demands of VDT work. You also tend to blink less rapidly when working for long periods of time without rest. A less rapid blink rate causes your eyes to become dry over time. To help alleviate this problem, you should consciously try to blink your eyes more often. Also, you should periodically look away from your screen and focus on an object in the far distance.
Many VDT operators complain of tired eyes. Some reasons for tiredness are prolonged concentration, stress, not getting enough sleep, allergies.
Sore eyes can be characterized by swelling or puffiness around your eyes. If your eyes feel sore or puffy, you should see your eye care provider immediately.
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Other factors that contribute to eyestrain are glare, improper lighting and poor adjustment of the VDT monitor.
The four major vision problems that contribute to eyestrain are: farsightedness, nearsightedness, astigmatism and alignment.
Farsightedness (hyperopia) is the condition where you can see objects clearly in the distance but not up close. Prescription lenses can correct this condition.
If uncorrected, farsightedness is a concern for VDT users. It can cause poor posture due to awkward positions that you may have to assume in order to see small characters on the monitor clearly. This can cause muscular aches and pains.
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Nearsightedness (myopia) is the vision problem that allows you to see clearly up close but not in the distance. This is just the opposite of farsightedness. Like farsightedness, prescription lenses can also correct this problem. Uncorrected nearsightedness is not as problematic for VDT users as is farsightedness.
Improper curvature of the eye lens causes astigmatism. This produces an image that appears out of center. To compensate, some VDT users may tilt their head at an angle while viewing their monitor. This can lead to awkward postures causing muscular aches and pains. Special corrective lenses are used to correct astigmatism and alleviate this problem.
Double vision results when both eyes are not properly aligned. This causes VDT users to strain when focusing on their monitor. As a result, eye strain, headaches and fatigue can occur. Corrective lenses are used to compensate for the deviation of the eyes.
As we age, the lenses in our eyes begin to harden. Focusing on objects close to us, becomes more difficult. The medical name for this condition is presbyopia. This problem occurs very slowly over time and effects each of us differently.
Presbyopia becomes increasingly noticeable as we approach 40 years of age. Using a VDT does not cause or accelerate this problem but it could bring it to our attention.
Therefore, as a VDT user, it is particularly important to have an eye examination. It is also very important that you tell your eye care provider that you use a VDT. Your eye doctor can then prescribe the proper eyeglasses for your situation.
Many vision problems are corrected with prescription eyeglasses. However, most eye-glass prescriptions do not consider the focal distance necessary for VDT work. Common prescriptions are quite adequate for reading and viewing distance, but not for the 18 to 24 inch ranges recommended for properly viewing your monitor. This is particularly true of VDT users age 40 and over who may suffer from presbyopia, which is the inability to focus up close.
Bifocal or trifocal users have problems focusing on the monitor. They can also suffer from poor posture due to having to bend their head awkwardly to focus properly. This can cause muscular aches and pains particularly in the neck and shoulder areas.
Fortunately, there are special VDT eyeglasses, which can be prescribed to help alleviate these problems.
Monofocal VDT eyeglasses, which have a fixed focal length, can be prescribed for the specific distance, in inches, to your VDT monitor screen. These eyeglasses are appropriate for proper monitor viewing distances. However, this type of eyeglass will not be useful for other purposes such as reading.
Monofocal VDT eyeglasses also allow comfortable viewing of the keyboard and items on a desk. However, the glasses should be removed and replaced with your regular prescription eyeglasses for other types of viewing.
Bifocal VDT eyeglasses can be used for comfortable viewing of the monitor and for other work. The upper portion of the bifocal lens is for viewing the monitor and the bottom portion for other (closer) work. As with monofocal VDT eyeglasses, your regular glasses should be used for other purposes.
In most office areas, lighting will not be a problem. However, improper lighting in your work area can affect your vision and contribute to eye strain and discomfort.
Light levels are measured in units called "lux". Some lux levels include: bright sunlight is about 100,000 lux, a 100-watt light bulb at 3 feet is about 1500 to 2000 lux and a full-moon on a clear night is about 0.1 lux. For general office work, 400 to 800 lux is a recommended level. Most VDT users prefer lower light levels between 100 to 500 lux. This improves the monitor screen contrast and aids in preventing eye strain and discomfort.
A task light is an adjustable lamp used on your desk top to illuminate small areas. This type of lighting is particularly suitable for focusing light on your paperwork but not on your monitor. You should be careful to make sure this light does not produce glare or reflections on your VDT monitor.
Glare is an annoying reflection of a light source on your VDT screen. There are many sources of glare. It can come from overhead lights, windows and light reflected from materials on your desk or even from your clothing.
To reduce or eliminate glare, you should locate your monitor so that it is at a right angle to the light source. When the light source is an exposed window, your monitor should be positioned with the screen perpendicular to the window. If this is not possible, try covering the window.
Another
method to reduce glare is to use an "anti-glare" screen over your
monitor screen. However, some "anti-glare" screens can be the source
of other problems. Some screens reduce the contrast and soften the image on the
monitor. This can contribute to eye strain and discomfort. Before using these
types of devices, you should try to eliminate the glare by properly positioning
your monitor on its tilt and swivel base.
A monitor hood which rests
on top of the monitor and projects out from the tops and sides of the screen can
also be helpful in reducing glare, particularly from overhead lights.
Finally, if you are
considering purchasing a new monitor, you may want to consider a monitor with a
flat screen. This will help reduce reflections by eliminating the curved surface
that is found on most monitors.