Here's a 9 page pdf summary.
The Effects of Computer Use on Eye Health and Vision
The color of computer screen characters may also affect their ease of visibility. The
color of the characters can affect how the eyes focus on the screen and may bring
about the development of harmless, but annoying, after-images for some individuals.
Monochrome, or single color, displays often provide more legible images for word
processing or data entry/acquisition tasks. Negative contrast computer displays (dark
letters on a light background) generally provide a more legible image than positive
contrast displays (light letters on a dark background). Either black characters on a
white background or white characters on a black background have been found to be
more visible than green, yellow-orange, blue or red characters. 20
The summary consists of a lot of hand-waving, but the sources used to create the summary might have some recommendations based on research,