I've tried all kinds of combinations for coding over the past 10 years. The only combination which didn't start to hurt my eyes over time was a light grey background with dark text.<p><a href="http://jlongster.com/media/images/screen.png" rel="nofollow">http://jlongster.com/media/images/screen.png</a><p>I absolutely love this scheme. It may not look pretty at first, but it's very very easy on the eyes, and also very clear. Colors are easy to make out and there's no glare anywhere.
I like dark on light; it's literally easier for me to read (though there is a medical cause for my choice).<p>I have Keratoconus, so there are very few corrective lenses which can actually help me have good clear vision. Light screens with black text cause my pupils to contract, which results in better focus (it's related to the reason that pinhole cameras work without any lenses).<p>If I do light on dark (my favorite colorscheme was Zenburn), the text gets too fuzzy to read at anything smaller than 14 point. On the other hand, if I use dark on light (I prefer bclear now) I can read text comfortably at 8 point.<p>It's certainly painful on the eyes if the rest of the environment is dark, but if you have a reasonably well lit room, I've noticed very little eye strain.<p>While my experience obviously does not carry over well to the population at general, it could help explain why dark on light is easier to read - it's easier to make out the details.
I wonder how much of the effect is because black on white is actually superior, and how much is because people have so much more practice at reading black on white. It would be interesting to see the studies repeated, using sub-groups that are used to black on white and white on black, respectively.
I find it easier to read prose when it's dark text on a light background, but I find it easier to read code when it's light text on a dark background. Maybe it has to do with proportional vs. monospace fonts?
Which ever background you pick, I find f.lux ( <a href="http://www.stereopsis.com/flux/" rel="nofollow">http://www.stereopsis.com/flux/</a> ) to be invaluable when using computers for extended periods of time (especially in the winter when the sun sets early). The quick rundown is that based on your location is adjusts the brightness and color temperature of your screen to match the lighting around you as it transitions from daylight to inside lighting. It's a slow transition so you don't really notice it until you look at someone else's screen and notice that it's looks really blue. The biggest downside I've seen is that it can't control the brightness of all displays (my MBPs screen gets dimmed but the Dell 2405 stays at the same level). It still does adjust the color temperature on external screens (at least on mac laptops it seems) which is better than nothing.
I've known people with vision problems who have to skip light-on-dark web pages because it's just not tenable for them to try to read. (This was before Readability, though keep in mind it's nobody's obligation to find a work-around for your eye-straining website.)<p>I suspect there's an objective benefit, there.<p>Everything seems to indicate that dark-on-light is better than light-on-dark, and both are better than light-on-light or dark-on-dark. (Or, in other words, contrast is vital, and dark text is preferable.)
I've always liked the way flarp looks (<a href="https://github.com/mikecrittenden/flarp-gedit" rel="nofollow">https://github.com/mikecrittenden/flarp-gedit</a>) . It's light on dark, but using colors that are easier on the eyes than plain white-on-black. There's a screenshot of it here: <a href="http://mikethecoder.com/post/861539191/flarp-a-gedit-color-scheme" rel="nofollow">http://mikethecoder.com/post/861539191/flarp-a-gedit-color-s...</a>