Computer Vision

Computer Vision Syndrome effects 75 million people

According to the American Optometric Association (AOA), Computer Vision Syndrome (CVS) is "the complex of eye and vision problems related to near work which are experienced during or related to computer use." In other words, you work on a computer for a while and your eyes bother you!

CVS syndrome consists of:

• Fatigue
• Headache
• Dry eyes
• Eyestrain
• Blurred vision
• Neck pain
• Backaches
• Double vision

If your vision is good at distance with or without glasses or contacts, you must change how your eyes focus from that far distance to the computer monitors closer distance. That requires muscular effort and prolonged muscular effort can cause problems. Try holding a brick in your hand with your arm held horizontal for a while. It gets real difficult real fast. The eyes have the same problem trying to maintain focus for a long time.

As we get older the lens in the eye that does the focusing for near gets stiffer and stiffer. By the mid-forties we all have difficulty getting the lens to change shape to focus at near If you are nearsighted you may find it easier to focus on the monitor by removing your glasses or contacts. However if you are nearsighted too much you may find you have to come too close to the monitor for comfortable vision.

When the visual demand of using the computer exceed the ability of the user to meet that demand, symptoms of CVS are noted. Poor contrast, glare and reflections all make CVS worse.

Letters on a VDT screen consist of round pixels of light forming letters, which are not sharply defined on the edges, instead of solid lines as in normal print. This can create difficulty for the brain to accurately control focusing effort, resulting in blurred vision. Other causes of CVS are poor lighting, inadequate viewing distance and an improperly designed workstation.

Ergonomics: Lighting in most offices is too bright for comfortable computer use. If you can reduce the lighting some it will help. Watch for glare from doors, windows or reflected glare from surfaces. Relocate any lamps that cast a glare on your screen. Cover windows with blinds or drapes. Glare reduction filters and hoods also help. If you wear glasses when working on the computer they should have an anti-glare or anti-reflection coating on them.

To minimize strain and eyestrain you should sit at a 90 degree angle, with your arms reaching to the keyboard at a 100 degree angle. The keyboard should be slightly below elbow height. Wrists should not be bent when typing. A wrist pad will increase comfort and may help prevent Carpal Tunnel Syndrome.

Your knees should extend four to six inches off the edge of the seat and bent at a 90 degree angle. Use an adjustable chair with full back support. Raise it so your knees are slightly below the level of your hips. Get a taller or shorter chair as needed. The VDT screen should be 20 to 30 inches away from your eyes. You should be looking slightly down at a 15 degree angle.

A frequently seen problem is people placing the monitor on top of the computer. This usually results in the monitor being too high. It's better to place the monitor on your desk and place the computer on a shelf or next to the computer in a vertical stand.

If you also have to see printed material it should be put on a holder next to the screen so it's at the same distance as the monitor screen.

In many offices the air is dry due to air conditioning and heaters. To make it worse  when we stare at a computer our rate of blinking reduces allowing the eye to become dry. This can cause a "dry eye" problem which makes the vision blur or the eyes to tear. Lubricant eye drops often help.

Electrostatic attraction attracts dust to the screen and eventually hinders visibility. Clean the screen often. A flickering screen also strains the eyes. Sometimes screen flicker can be reduced by plugging other appliances and lights in different outlets to prevent electronic interference. Also, make sure all your electrical cable connections are tight. Every once in a while readjust your monitors brightness and contrast.

Warning:

What's your computer doing to your eyes? One disturbing result of prolonged computer use has been noted. I have seen many people that have had perfect vision for years and a few months after starting a new job with extensive computer time they start to become nearsighted and their distance vision becomes blurry.  When this starts to happen glasses can be prescribed to reduce the visual stress. It's the staring at the screen for long periods that causes the greatest stress. Take a visual break every 20 minutes, mixing in non-computer tasks whenever possible.  Have your eyes examined.

If you are have symptoms of CVS, special glasses can be designed to help your eyes handle the visual stress of computer use.