While working in front of computer monitor or a laptop, should the lights in your workspace area are powered on, in dim light, or turned off?

Any possible causes or risk in our eyes when the lights are powered on, in dim light, or turned off?You personal vision problems can be a factor. But in general, the light  in a workplace should be bright and well dispersed. Glare should be reduced.
Some sources commender 500 lumen at the desktop. (This can start a debate.)
This REFERENCE is just the tip of the light-berg.
http://shadesbreath.hubpages.com/hub/Workplace-Lighting---Office-LightingI was starting to think the above link was going a little overboard when it started to talk about "feng shui" and this:
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Extroverts generally have a higher threshold for sensory stimulation than introverts do, which means extroverts aren’t as affected by bright lights or loud noises. Introverts tend to prefer less stimulation, and are more affected by sensory input. Introverts also tend to be easily DISTRACTED by their senses. Bright lights and loud noises wear them out. In CONTRAST, extroverts are more comfortable in the midst of a 'gong show.' Their performance and mental state may not be as negatively INFLUENCED by sensory stimulation.
If you’re an introvert at work, make sure your office or space offers low amounts of sensory stimulation. (Pawlik-Kienlen)