My astigmatism gives me doubles in any high contrast situation, whether light on dark or dark on light. Solarized/Zenburn type low-contrast palettes are the only thing that really addresses it.
I've noticed that when my eyes are tired as well. I think well-considered low-contrast color schemes don't get enough love, and I'm still a fan of Solarized, too. (Although my favorite schemes, both light and dark, are Spacemacs'.)