Flashes of light lasting a few seconds may appear in your vision when the vitreous gel pulls or tugs on the retina. This may happen as a natural result of aging or it may occur temporarily if you receive a blow to the head or eye. Usually these flashes, which are often described as lightning streaks, are noticed at night.
Light flashes appearing as wavy lines in both eyes and lasting from a few minutes to half-an-hour, are usually a sign of an ocular migraine headache. Migraine-related flashes are often noticed in a lighted environment. Flashes of this nature are not a symptom of eye problems. If you suffer from ocular migraines, contact your family physician for assistance.
The onset of new light flashes of short duration at night, especially when accompanied by the appearance of many new floaters or a blackening out of part of your field of vision, may indicate a retinal tear or detachment. If you experience light flashes in combination with these symptoms, you should contact your eye doctor immediately to arrange for an examination by a retina specialist.