|MadSci Network: Neuroscience|
Although I'm not a vision scientist, I have done some research to help me answer your question. Hopefully I can at least point you in the direction of some more questions you can ask.
It seems that in the 1980s two researchers (Olive Mears and Hellen Irlen) discovered that for some people, color can affect reading performance. This started a whole line of research into who it could help, how it should be used and why it works. Many of these questions are still unanswered and while some people are skeptical, others believe very strongly that color can be useful for many people. The American Optometric Association recently wrote a statement reviewing the research and what they think about it. They're more on the side of the skeptics. You can also read more about the issue on wikipedia.
From what I've read, for some people using colored paper, or more often transparent colored overlays or tinted glasses, can speed up reading time. But it won't necessarily work for everyone. It seems to only be beneficial to people who report having some trouble with reading, specifically people who report seeing some kind of visual distortion on the page. Some of these people might get headaches when they read or feel like their eyes are tired. This is sometimes called Mears-Irlen syndrome or Scotopic Sensitivity Syndrome (SSS) and is itself controversial. There are lots of other reasons that someone might have trouble with reading that color would not help at all. For example, dyslexia is a common source of reading difficulty. Although some people say that colored lenses help people with dyslexia, it seems like it helps about the same proportion of people with dyslexia as without so it's more likely that dyslexia and SSS are separate problems. The general consensus in the scientific community is that dyslexia is a problem with processing and representing the sounds that make up words and not a problem with vision.
You asked about lenses versus paper, and the color blue specifically. Here again there seems to be disagreement. Some researchers think that the color of the lens needs to be specifically chosen for the individual and it won't work if it's a little bit off. On the other hand, most of the time the optimal color is somewhere in the blue to green range and other researchers report benefits with blue in general. I only came across mention of one study that used paper color with similar results, but that study was not published.
To me the most interesting question is why color might affect reading, and this is where the brain comes in. Some people think that it has something to do with deficits in the magnocellular pathway which is a pathway for information to flow from the retina (in the eye) to the visual processing centers in the brain. (Here is a description of visual pathways and ganglion cells). This pathway is actually not thought to processes color at all, but rather motion. It is not clear exactly how introducing color to reading fixes this (maybe it reduces the amount that this pathway is relied on?). Another explanation is that adding color changes which part of the visual cortex does most of the visual work of reading. Yet another explanation is that people who benefit from color really have a problem with how they focus or move their eyes (accommodation and occulormotor problems).
If you want to do more research into this phenomena, I would suggest you start with the magnocellular and parvocellular (color vision) pathways and see what you can learn about them (also look for the recently discovered koniocellular pathway that may respond to blue light alone). If you have access to scientific journals through a library I would also suggest reading the references from the AOA statement and look up any terms you don't understand (they can be a bit technical). There are many unanswered questions in how the brain processes color and other visual information, so keep asking.
Try the links in the MadSci Library for more information on Neuroscience.