I get eye-strain headaches sometimes, and it really sucks. A lot of this has to do with the black-on-white default settings that VS uses. The good news is that you can changes this :).
A lot has been written about IDEs and their colors, and none (to me) is more impressive than TextMate's Vibrant Ink:

I really like the Monaco font, and the black background cuts down on the overall glare. Jon Lam recently created the Vibrant Ink theme and released it on his blog, but he also included his full settings which for some (me included) were a little much. I tweaked his theme a bit by adding in the Monaco font (pictured above) and raising the pure black a few shades so the contrast isn't as drastic:
I've attached below the theme I use, plus two others I really like - MidTones (you can see more here) and Jeff Atwood's super groovy settings (codenamed Pruno).
In addition I've included the Monaco font (pictured above) - to install just drag it into your System/Fonts folder.
