I too get the aura without the headache. They start as a small area of no vision, then grow, in the form of a 'C' or backwards 'C', depending on which eye they are in. The C letter consists of a scintillating, jagged series of lines. Mine eventually grow out of the field of view, and that is the end. They do interfere with my vision when they are there; not only the jagged scintillations, but areas of no vision along or inside the C or backwards C shape.