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Extensive testing in government laboratories has established that video display terminals(VDTs) emit little or no harmful ionizing radiation (such as X-ray) or non-ionizing radiation (such as ultraviolet) under normal operating conditions.

In fact, the amount of ultraviolet radiation produced by VDTs is a small fraction of that produced by fluorescent lighting. The levels of radiation from VDTs are well below those required to produce cataracts or other eye damage even after a lifetime of exposure.

Some people will temporarily notice that black and white objects appear tinged with color after viewing VDTs for an hour or more (this is called the McCollough Effect). These colors are usually complimentary (opposite) to the color of the VDT characters, and are not a sign of an eye disease, damage to the eye, or eye strain.

Can VDTs be associated with eye strain?

VDTs are associated with eyestrain. You may notice a variety of symptoms including eye irritation (red, watery or dry eyes), fatigue (tired, aching heaviness of the eyelids or forehead), and difficulty focusing. Headaches, backaches, or muscle spasms can also occur. These complaints can often be relieved by either changing the arrangement of the workstation or providing proper glasses for the user.

Though eyestrain is an annoying symptom, it does not mean that continuing to work on a VDT will damage your eyes. To find relief, you should first make a systematic search for the cause. Your ophthalmologist can examine you to rule out eye disease and provide proper glasses if you need them.

The distributor of the VDT equipment, specialists in workstation ergonomics or agencies such as the Occupational Safety and Health Administration (OSHA) may also provide helpful suggestions regarding workstation modifications to prevent the symptoms.

How can eyestrain be prevented?

At the workstation, most VDT users prefer their screen to be a little farther away than they normally read. The top of the VDT screen is most comfortably placed at or slightly below eye level. The reference materials should be as close to the screen as practical to minimize head and eye movements and focusing changes.

Lighting should be arranged so reflections and glare are minimized. Sometimes standard office lighting is too bright for comfortable VDT use. If it is not practical to modify your office lighting, hoods and neutral density or micromesh filters for the VDT may help. The VDT screen is a good dust collector and should be wiped often with an antistatic cloth to improve visibility.

Periodic rest breaks are important. Use of a VDT requires a fairly unchanging body, head, and eye position which can be fatiguing. Frequent blinking will lubricate the eyes and prevent them from drying out.

What are the special vision needs of VDT users?

The VDT screen must be kept in proper focus. Since the screen is usually placed farther away and higher than the usual reading distance, different glasses may be necessary. This is especially true for individuals who wear bifocals, trifocals or reading glasses. A bifocal height may need to be raised to compensate for the higher positioning of the VDT. The additional visual demands of VDT use may mean that some individuals who normally do not need glasses should have corrective lenses for this activity.

Your ophthalmologist can prescribe the correct glasses for you. You will need to describe the layout and dimensions of your workstation for the ophthalmologist to calculate the lens power that will work best for you.

In addition, the comprehensive medical eye examination you receive from your ophthalmologist will help diagnose whether the discomfort you experience with VDT use is due to simple eyestrain or whether unsuspected disease is present.

Source: American Academy of Ophthalmology