TO my knowledge, other than things like adjusting the display and using apps like cleartype, it's pretty much up to the display you're using.
Any type of LCD display means the manufacturer using several tricks and compromises to get viewers something resembling a std CRT. Unfortunately, these same tricks and compromises make it less ideal for regular text. My desktop LG display has additional compensation built-in as a separate mode to make plain text more legible, & it is easier to read than many others. I'd assume the Kindle is designed without all those features to make colors look good, with engineers focusing instead on just text.
Since you obviously can't just switch displays, the only other solution I could imagine would be to check out some of the anti-glare &/or privacy filter screens they make for laptop displays... They can make a difference, though I don't know whether or not it'll help, or how much in your situation.