Protect Your Eyes When Using a Computer
Since the majority of us spend hours in front of a computer monitor, it is good practice to protect your eyes from potential damage. Keep in mind that the following recommendations apply only to properly setting up your workstation to best protect your eyes and does not address other ergonomic needs related to working in front of a computer.
Taking Proper Care of Your Eyes
1. Take five-minute breaks every hour by looking off into the distance and looking away from the computer monitor.
2. Just close your eyes for a few minutes when your work requires prolonged data input into the computer.
Keeping Proper Distance and Other Safety Measures
3. Keep the distance of the monitor from your eyes between 16 to 30 inches. Most people find a distance of 20 to 26 inches comfortable.
4. Make sure that the top of the monitor is at a level slightly below the horizontal eye level.
5. Tilt the top of the monitor away from you at a 10- to 20-degree angle. Most monitors are provided with tiltable display screens, which enable you to tilt the monitor to create an optimum viewing angle.
6. Keep your screen free of dust and fingerprints.
7. Use an adjustable chair that enables you to sit at a proper angle and distance from your computer monitor screen.
8. Use document holders to secure any reading material or reference material, if your work involves prolonged data entry. Place the document holders close to the monitor and at the same distance from your eyes as your monitor. This enables your eyes to remain focused as they look from the monitor to the reading material.
9. Use a work surface whose height is 26 inches from the ground.
10. Keep the distance from the front of your chair to the hollow of your knee between 2 to 4 inches.
11. Use a character size that is visible. The character size is an important factor since it determines the distance at which the user prefers to view the monitor.
Changing the Appearance of the Text Fonts on Your Computer Screen
12. Point your cursor anywhere on your desktop and right click on Properties. The Display Properties window appears.
13. Click the Appearance tab on the Display Properties window.
14. Go to the Font Size pull-down menu and choose either “Large Fonts” or “Extra Large Fonts” instead of the “Normal” font that has already been pre-selected by default. That is, if you are working on a Windows XP system. Once you have made a choice, you will see a sample of what you have chosen in the upper part of the Display Properties window. Choose what is comfortable for your eyes.
15. Click on the Apply button.
16. Close the Display Properties window.
Ensuring Proper Lighting
17.Use fluorescent tubes to achieve lower illumination levels. Higher illumination levels wash out the image on the screen. Illumination levels refer to the amount of light falling on a surface measured in lux or foot candles (metric and English systems of measurement respectively).
18. Provide supplementary task lighting through lamps. Task lighting allows workers to adjust the illumination level according to their own preferences, if the illumination level is below the suggested ideal of 50 foot candles.
Ensuring Proper Lighting by Adjusting the Contrast
19. Contrast is the difference in luminance between two areas (the task area and the background area). Prevent excessive contrast within the visual field and reduce the contrast to acceptable
limits by avoiding extremely dark or bright surfaces. The primary reason for this is that vision problems could arise and viewing become difficult when there is high contrast between task and adjacent surroundings.
20. A good display screen also has separate contrast and brightness controls. Adjust the brightness of the background in relation to the characters by adjusting the contrast controls.
21. Control the amount of light emitted from the characters themselves by adjusting the brightness controls.
Ensuring Proper Lighting in Your Work Environment To Prevent Glare
22. Glare is caused by non-uniform distribution of luminance within your visual field, as well as bright luminaires or windows. You can prevent glare by reorienting your work station and moving the sources of glare out of your line of sight.
23. Cover windows with Venetian blinds, draperies, shades or filters to reduce glare from sunlight or the luminaires in your work environment.
24. Use panels to block the intensity of light, thereby reducing glare.
25. Adjust the computer’s contrast knob to change the brightness of the screen and characters, which will also reduce glare.
Position the screen at right angles to the source of light.
Avoid wearing bright clothes which may cause a glare by causing a reflection on the screen.
Cover your monitor ith an anti-glare screen.
Ensuring Proper Lighting in Your Work Environment to Prevent Reflective Glare
When a worker can see a light on the surface of his or her screen, this is the case of reflective glare. This glare can also be seen on smoothly polished desk tops. The sources of reflected glare can be windows, reflective walls, luminaires or reflective clothing. You can control the reflective glare by the methods suggested in each of the steps below.
Reduce the intensity of light source by providing louvres for luminaires, by covering windows or by choosing appropriate height panels.
Provide a matte or flat finish on furniture equipment or walls.
Tilt the monitor to remove the reflection away from your line of vision. Tilting features are now included in most terminals.
Cover the screen with an etched surface or with different types of filters.
Rearranging the Office to Reduce Lighting Problems
Position the workstations between rows of luminaires.
Place the workstations away from the windows.
Place all workstations parallel to the windows.
Use panels to block light.
Selecting Video Display Colors to Avoid a Vision Problem Called McCullough Effect
When the color of the video display screen is green, some users see pink afterimages. This is an unusual phenomenon called the McCullough Effect. The condition causes people who use computers for hours to see a pinkish fringe around certain images. Although this is a harmless afterimage, the afterimage is created when the retinal nerve cells that perceive the color green become saturated and the color red appears instead. Choose video displays that are not green in color to prevent this vision problem from occurring.