You could convert your books to epubs, and change the font.
You could also make your whole ebook bold, so all the text will show fatter.
I found on my Ez-Reader Pro one font type that is very viewable! (ft 2, forgot the name).
If your screen looks green, try reading it under a purple light or something to compensate.
Red, yellow, or even blue backlight can change the background color a bit.
On a cloudy day, my Jetbook had a little tint of brown in the grey.
Under white LED light, it looked more grey.