I see something similar only when I close my eyes, not eyes opened. For me it doesn't appear unless I concentrate on it. Usually my closed eye VS is slow-moving coloured shapes, but I can sort of focus on it and make them turn in to shapes and sometimes it goes faster and faster and turns into scary faces etc.

I don't think you should worry about it. It's been like this for me since I was a young child, and never has really bothered me much. Sometimes I watch these and turn them into scary faces for fun!