Flashes are sensations of light, when no light is really there. They may appear as many tiny bright lights (like “sparklers”) or like flashes of lightening.

Flashes may occur when the vitreous jelly pulls on or tears the retina. These flashes usually last for only a second or so, but typically occur repeatedly. They may be more obvious with eye movement, or in a dark room.

Some people with migraine headaches may experience a different type of flash. These are usually shimmering, jagged lights that are present constantly for a period of fifteen minutes or so. They typically appear in the center of your field of vision, and progress slowly towards the edges of the visual field. A headache that is commonly throbbing, and on one side of the head, may follow the disappearance of the flashes.