phosphene

Phosphenes are the luminous floating stars, zigzags, swirls, spirals, squiggles, and other shapes that you see when closing your eyes tight and pressing them with your fingers. Basically, these phenomena occur when the cells of the retina are stimulated by rubbing or after a forceful sneeze, cough, or blow to the head. The word phosphene comes from the Greek words phōs (light) and phainein (to show). Phainein is also a contributing element in such words as diaphanous, emphasis, epiphany, and phenomenon, among others.