When you hit your head, you may see stars or flashes. Is there a specific name for them?
Seeing flashing lights is called photopsia. But "seeing stars" is a perfectly normal way of referring to the phenomenon.
This is one of several types of entoptic phenomenon : visual effects whose source is within the eye itself
Many people also use "knockout stars", as seen in cartoons when a character is knocked out. The character sees stars swirling around his or her head.