The 209s give a small flash, certainly enough to see, especially in a dark building. You say lost his vision I assume you mean it was abit blotchy for a while as I have yet to see a grenade blind me completely (play at the Gaol so have had a fair few grenades land next to me in that time)
20171225_175837.mp4
Video is me testing a trmr on 209s and shows the flash