different types of monitor strain

I got a call from a man who has been in the development business since the 70s. We got to talking about a whole lot of stuff (actually it was more listening on my part then anything else). On the topic of eyestrain (?) he said that different colors (primary?) have different focal depths, so at least for some people strain is caused when looking at a color monitor w/fine dot pitch. I have to at least take him at his word on that, but when I mentioned that staring at green phosphors for an extended length of time (>30 minutes say) caused white to appear pink. For instance the numbers on a cars speedometer. He said he never experienced that. Can anyone explain the reasons for that? It stands to reason that causing your eyes to focus on something small? and multichromatic would cause strain (you're forcing your eyes to focus on a single point that in essence appears to be at varying distances. I don't understand the pink eye effect though.