How can we distinguish scintillations and flashes in vision?

Context: The clear gel that fills eyeball is normally attached to all parts of the inside of the eye. As we get older it can become more liquid (watery) and detaches from the back of the retina causing flashes as it pulls on the retina ; floaters. This is made worse when reading, looking side to side, basically with eye movement. Scintillations occur with atypical migraine- with or without headache.

Flashes due to a : To a retinal tear can be isolated to one eye. On the other hand, a scintillating scotoma lateralizes to one side equally in both eyes. This is due to the location of the vessels in the brain that are affected. This is sometimes called a homonymous field defect. While a flash can appear like a bright light, a scintillating scotoma results in partial loss of sensory perception in both eyes.