Vitreous detachment/ Eye floaters -- These are those dots you see when you blink after staring into the sun or bright light. It's another view on an image that your brain/eye can create. When playing with the projectors, these eye floaters come into play.
Eye floaters can sometimes occur after cataract surgery. Even if you haven’t been treated for cataracts these nay occur as part of aging and are usually nothing to worry about.