My visual migraines (or at least vision issues I've had that have definitely linked to migraines) have been seeing a slowly emerging crescent moon shape in my left eye, which almost looks prismatic, then it fades away (the rest of the eye's cloudy gray, which also comes and goes) - all within the span of 20-30 min.

Otherwise, seeing a seemingly centered halo of white light with a black center. THAT was scary.. and came immediately following a horrible charlie horse in my leg (that was during my 3 month stint on Yasmin - evil pill).

I've seen these flashes of blue/green hues that you're referring to though as well, I just never linked them to the MS, I thought they were related to looking at TV/PC monitor too long (white background to darker area, for example). I noted them within the past couple days happening with more frequency, and last night my left side (arm/hand) started the tell-tale pins & needles, and I ended up in bed with a left side migraine throbbing in my temple, that spread a good portion of my forehead. It took everything to think about something to distract from the pain and nausea. Luckily I was able to sleep, but I still have pins & needles a bit in my left side and fingers today, and a bit of a headache still left.

So that's interesting that the flashes of 1 color can also be migraine. Good to know!