The blue field entoptic phenomenon

Entoptic phenomenon

Entoptic phenomena are visual effects whose source is within the eye itself. In Helmholtz's words:...

or Scheerer's phenomenon (after the German ophthalmologist Richard Scheerer, who first drew clinical attention to it in 1924) is the appearance of tiny bright dots (called "blue-sky sprites") moving quickly along squiggly lines in the visual field, especially when looking into bright blue light (such as the sky). This is a normal effect that can be perceived by almost everybody.