iOS 6 looked better, worked better, and you could read off it without getting eyestrain or migraines. Heck you could even use the music controls on the lock screen.oh and the iPod/Music app actually worked.
iOS 7 caused me to throw my iPad4 in the trash a week after installing it. And I have zero interest in replacing it. My iPhone5 went from heavy usage to I barely touch the thing because the bright white they use makes my eyes turn blood red almost instantly. The intensity is so bright that the Babies R' Us color scheme has a blurry/foggy effect. I don't know how anyone can look at it and find it remotely appealing.
Wow you're bitter. And wasteful apparently. Why you would throw away an almost new iPad without trying to sell it... well, I'll refrain.
You can invert colors which is a meh solution to your eye strain, but for reading etc it will surely help tremendously. Do you know how to set up your home button to activate invert colors? It makes it very quick and easy.
Or bring brightness way down. There's no reason your eyes should strain like that if brightness is very low, if they do I would recommend seeing a doctor as the type of reaction you're describing is extreme and might warrant some attention.