Lighting Problems

A very common reason for discomfort glare being a problem for computer workers is lighting. Light often leaves the overhead fluorescent fixture in a wide angle, resulting in light directly entering the eyes of the workers.

Good lighting design can significantly help reduce discomfort glare. Light leaving the fixture can be directed so that it goes straight down and not into the eyes of the room occupants. This is most commonly accomplished with the louvers in the luminaire or fixture. An even better solution is indirect lighting in which the light is bounced off the ceiling - resulting in a large low luminance source of light for the room.

One way to test for glare discomfort is to have the worker look at their computer screen and be aware of any bright lights in their peripheral vision. They the can use their hand to shield their eyes like a baseball cap visor and note whether they sense an immediate improvement in their comfort. They should try this 2-3 times. If they notice an immediate sense of improved comfort by eliminating the lights from their peripheral vision, then they are experiencing glare discomfort.

Solutions to glare discomfort:

If bright lights are deemed to be contributing to discomfort, then they should be removed or mitigated in some manner. There are several ways in which they can be improved.

    * Turn off some of the offending fluorescent lights. Sometimes it is a single fluorescent fixture in the ceiling which is just in front of the person. Very often a single offending fixture can be turned off without creating lighting deficiencies.
    * Fluorescent light fixtures can be retrofit with parabolic louvers which direct the light straight down into the room. The parabolic louver (the louver is the egg crate-like cover that directs light into the room) directs the light from the fluorescent tubes straight downward, hence it is not directed into anyone's eyes.
    * Re-orient the work station so that bright lights are not in the field of view. Sometimes the work desk can be rotated 90 or 180 degrees so that the fluorescent lights or bright windows are not in the field of view.
    * Wear a visor. This is actually a very efficient way to eliminate the brightness of overhead fixtures. A person can wear a visor for a day or two as a test to determine the extent to which the light problem alleviates discomfort at the end of the day.
    * Avoid bright reflective surfaces. In some work environments, the desk tops are white. This results in the desk top surface becoming a discomfort glare source. Desktops and other furnishings should have a matte, medium reflective surface.
    * Use blinds or drapes on windows. This is often the most difficult to implement because people like the views out of windows. However, if the view out the window is considerably brighter than the objects in the room (as it almost always is) then the window is serving as a discomfort glare source.
    * Evaluate whether auxiliary lighting (for example a desk lamp) on reference documents is causing glare discomfort.
    * Change the brightness of the screen. The brightness of the screen should be adjusted to match the brightness of the visual objects which immediately surround it.
    * Hang or erect partitions. Very often the offending light sources can be eliminated from the field of view by erecting or moving partitions.

Teresa Lui, O.D.       Palo Alto Optometrist         Optical Boutique           650-321-9525          info@drteresalui.com