Seeing images with my eyes closed

For the past couple of months I've been seeing these weird images when I close my eyes sometimes. I'm not talking about seeing a few flashing lights or a couple of bright colours but extremely vivid moving pictures. It literally feels like when I close my eyes I open them in another world. I have seen busy streets with people and cars walking, a map of the world, a hockey game, a movie theater, the YouTube homescreen, someone's bedroom, and alot more though these only happen once in a while. When I'm see these things they are perfectly clear and I can see and look around in them. The thing is though they only last a couple of seconds and then they're gone. The most common thing for me to see is teeth. Everyday If I close my eyes for 5 seconds I will see pictures of teeth. Sometimes they're really crooked, sometimes they're really straight, sometimes it's someone smiling. Even though these are not as intense as the other ones I can still see them perfectly clear and I could even count the number of teeth if I had too. Has anyone else expericend something like this? People have been telling me it's normal but I'm not sure.