Approximately 70% to 75% of people who use computers on the job report complaints related to computer use. Some signs of computer vision syndrome include fatigue, headaches, dry eyes, inability to maintain near focus, progressive refractive changes, neck and shoulder discomfort, changes in color perception, and pain in or around the eyes.
When you work at a computer for any length of time, it’s common to experience eye strain, blurred vision, red eyes and other symptoms of computer vision syndrome (CVS). This is because the visual demands of computer work are unlike those associated with most other activities.
If you’re under age 40, eye strain or blurred vision during computer work may be due to an inability of your eyes to remain accurately focused on your screen or because your eyes have trouble changing focus from your keyboard to your screen and back again for prolonged periods. These focusing (accommodation) problems often are associated with CVS.
If you’re over age 40, the problem may be due to the onset of presbyopia — the normal age-related loss of near focusing ability. This, too, can cause CVS symptoms.
Computer glasses differ from regular eyeglasses or reading glasses in order to optimize your eyesight when viewing your computer screen.
Computer glasses include special lens coatings to reduce glare and a tint designed to eliminate eye strain.
Computer screens usually are positioned 20 to 26 inches from the user’s eyes. This is considered the intermediate zone of vision — closer than driving (“distance”) vision, but farther away than reading (“near”) vision.
Most young people wear eyeglasses to correct their distance vision. Reading glasses are prescribed to correct near vision only. And bifocals prescribed for those over age 40 with presbyopia correct only near and far. Even trifocals and progressive lenses (which do have some lens power for intermediate vision) often don’t have a large enough intermediate zone for comfortable computer work.
Computer Work Environment
The importance of a sound ergonomic work environment cannot be over-emphasized. Below is a checklist of things you might do to improve your work environment to minimize or eliminate discomfort while using a computer.
Many times, your chair can be adjusted to make your work station much more efficient and comfortable. For instance:
- Your feet should be flat on the floor (or on a slightly angled foot rest) with your knees bent close to or greater than 90 degrees.
- Your chair seat should support your legs without excessive pressure on the back of your thighs.
- Your back should be snug against the seat to fit your spinal contour.
- Your thigh to trunk angle should be 90 degrees or greater. The distance from the front of your chair to the hollow of your knee should be 2 to 4 inches.
- Your wrist and hand should extend nearly straight from the elbow to the home row of the keyboard.
Your Work Surface
Consider the following suggestions to make sure the height of your work surface and the amount of leg room it provides are “comfortable.”
- For most people, the amount of leg room below the work surface should be about 25″ height by 27″ wide by 27″ deep. Larger people will require more space.
- A commonly preferred work surface height for computer use is about 26″ as opposed to conventional 29″ of most tables or desks.
Your Monitor and Keyboard
The following suggestions will help you arrange your computer monitor and your keyboard to allow you to work most productively and comfortably:
- Locate your monitor 16″-30″ from your eyes, depending on the size of your monitor and your individual vision conditions. Many people find 20″-26″ most comfortable.
- The top of the monitor should be slightly below a horizontal eye level. Tilt the top of the monitor away from you at a 10 degree to 20 degree angle. The center of the monitor should be 10 degrees to 20 degrees below your eyes. This is 4″-9″ below your eyes at a distance of 24″.
- Keep your monitor free of fingerprints and dust. Both can reduce clarity.
- Place document holders close to your screen within the same viewing distance. Keep your keyboard and monitor in line.
- Adjust your keyboard tile angle so that your wrists are straight.
To improve visual efficiency when using your computer:
- Adjust the brightness of the monitor to an intensity that is comfortable to your eyes; not too bright and not too dim. Eliminate bright light sources from your peripheral vision.
- Next, adjust the contrast between the characters on the monitor and the background so the letters are easily read. Repeat the brightness adjustment and then the contrast adjustment.
- Minimize reflected glare on your monitor by using window treatments, dimmer switches on lights and anti-glare screens. Look for anti-glare screens that have received the American Optometric Association Seal of Acceptance.
- Position your monitor perpendicular to windows or other bright light sources to reduce glare.