[Nadya]

Strange, I find the exact opposite. I have to use Stylish to redesign any website that uses a dark theme precisely because of eye strain caused by reading high contrast backgrounds. White on black emphasizes this more than white on black when reading lines of text. [0]

[0] http://www.ironicsans.com/owmyeyes/

[lemmon7]

Ideally more software would have an option to use either a light or dark theme or customizable colors. Dark themes make eye floaters much, much more manageable, which is my main visual problem and a common complaint from heavy computer users. Can't speak for anyone else but that's my experience. It's also important to have good ambient light levels as well, which can affect things.