Environmental Health & Safety > Ergonomics > Injuries & Prevention > Eye Strain
Visual discomfort is a frequent complaint of computer workers. Eyestrain and headaches blurred vision are the most common problems reported. Other problems include double vision, burning and dry eyes, eye fatigue, light sensitivity, and after-images. Neck shoulder and back pain can also be related to viewing the computer keyboard and/or screen. The American Optometric Association has designated this complex of problems as computer vision syndrome (CVS).
Lighting and vision are inter-dependent. Workplace lighting and visual ability both play a significant role in work posture. Workers alter postures to relieve stress on the eyes. Complaints of neck, shoulder and back pain can frequently be alleviated if visual ergonomics are addressed.
Vision and Eye Problems:
Difficulties with focusing and eye alignment can result in eyestrain, neck pain and headaches during computer work. To avoid problems, have your vision checked by an eye doctor aware of problems that can interview with computer vision.
The type and location of the monitor you use plays a significant role in visual comfort.
Remember that the location of the visual target plays a major role in determining sitting posture. Visual requirements result in the user positioning the body so that the face is parallel to the viewing surface. This principle should be remembered when determining placement of a monitor.
The screen should be at least 20 to 26 inches distance. Adjust this distance for your visual acuity needs and comfort. The farther away the better in most cases. Distances of 30-40 inches are frequently preferred.
You should be able to view the screen with a slight downward gaze without tilting your head up or down. The top of the screen should be about at mid-forehead level. If you have a screen larger than 17”, the top of the screen may need to be a little higher.
Your face should be parallel to the screen. Setting the tilt will help to adjust the height. Be sure to test for excessive glare when tilting the screen. If you can see your image in the screen, reflections and glare will strain your eyes while working.
Your documents should be positioned close to the monitor, either close to the side or directly in front between the keyboard and the screen.
Brightness and Contrast:
The monitor’s brightness should match the room brightness. Begin making adjustments by reducing glare from sources in the room such as windows and overhead lights. Use light switches, blinds, curtains, filters or remove bulbs as necessary. Then adjust the brightness control on the monitor somewhere close to the monitor’s mid-range if possible. After adjusting the brightness, set the contrast to a comfortable level. Usually, the higher the contrast the better.
The clarity of your screen depends upon refresh rate, resolution and dot pitch.
Check your refresh rate and resolution for adjustment if necessary. They can be adjusted using the Settings tab in the Display properties dialog box in Windows.
Dot pitch is not adjustable.
Computer glasses correct your vision in the intermediate zone, the distance you normally sit from your computer screen. If you also require correction in the near and/or far zones, you will need to consider multiple focusing options.