I have the same thing happen. Seeing the prism light for about 20 minutes. It's an occular migranine. I've been to the doctor for it. There is nothing you can do just wait it out. Nothing hurts I just can't see very well when it's happening. If I'm at work I have to wait it out and close my eyes. It looks like a section of the paper is blocked out and I can't see the whole picture. Nice little light show though

I also have floaters. Have had those for many years. Now I have a new thing. If I'm really tired my left eye hurts like something is in it and it hurts to open it. Sometimes I feel like I can't open it. And then it waters really bad. I don't know what that is?????
Love,
Joyce