I get these shimmering a lot, so much that it’s became a part of my life. I guess throbbing could be a word to describe it too o r if I look at a TV from my bottom peripheral vision the whole picture is just "shaking". The only thing I'd be concerned about was a torn retina from the vitreous pulling on it which is what that shimmering is basically. I was reading up on that a long time ago and that is normal, common phenomena, but I forgot what it is that causes it, but that's not a problem either. I don’t know but it doesn’t seem common to me.
I have been checked recently, by a fairly good ophthalmologist because of shimmering phenomena too. He checked blood vessels, the optic nerve, the retina... but the shimmerings are very real. I am not someone who worries about his health much. The other things might be me being overconscious of my vision, but the shimmerings must have some cause. I just hope it's nothing neurological.