Technique to ease eye strain.  Turn window and browser backgrounds to solid black, and pick a light 'ArizonaColor' text color, such as light-tan, light-blue-grey, light-rose, etc.

Try it for one day.  You'll gain at least an hour before your eyes wear down. 

If you can't see the text well, keep lightening the text color.  It should be no more difficult to see than black-on-white.
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Your mileage may vary.  This really depends on the environment.  Sometimes having a black background accentuates reflections in the CRT glass, meaning your eyes have to constantly battle to stay focused on the screen content rather than the reflection.

An advantage to BlackBackgrounds is that there's less radiation coming from the CRT.
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Personally, I'm a fan of the old green-on-black scheme.  The ergonomics of green are documented.

''Green on black for high ambient light environments. Red on black for low light environments. Since most offices are lit up like a surgical operating theater, green-on-black is the usual.''

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I guess this would be popular in Soho. OTOH I do see a Hitchhikerish variation: there's a black command button on this black form, and when I click on it, a black dialog box comes up to let me know I did it.

''This was actually an old BBS trick - set the ANSI color codes for your message text to black-on-black, and you could send "secret" messages''

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I tried this and liked it, although at least once a day I have to change my colours back because some inconsiderate sod has used a partial specification of colours on their web-site, or has an image with transparent background and black lines.
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Oddly enough, this works well on LCDs and good CRTs, but cheap picture tubes seem to be less discriminate about where they throw their beams (oh dear) and the white text manages to be fuzzier than the black text.  Perhaps it's because I'm not looking closely at the blackness of the black text (that is, there could be some spillover from adjacent pixels and it won't be black but merely a dark something - the same thing happening to white text makes the all-important edges indistinct).  

Green-on-black works well on all sorts of displays.

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In many systems I have written, I use black background with four light colors - white for wysiwyg fields, lime for fields which translate typed input, like date fields, cyan for non-editable fields, magenta for labels. Most users love it. (Those who have the most common color-blindness - red - do have trouble with the magenta.) They like it because it gives them a lot of information intuitively, I like it because it is easier on the eyes.

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