Try this link. I know the address seems kinky, but it is legit. Trust me, I am a school librarian.
Flashes, which appear as lightning streaks, shooting stars, fleeting white pinpoints or blasts of light, are false bursts of light produced by optic nerves of the retina. Most adults experience flashes after age 50, as the vitreous thickens as part of the normal aging process and begins to alternately pull away from and rub against the light-sensitive retina. They also appear in those prone to migraine headaches, sometimes right before the onset of a migraine, and can also result from head trauma or by blood vessel spasms in the brain. As with floaters, flashes should be checked by an eyecare provider to ensure they’re not the early sign of a more serious problem
Thank you for the link. I'm 25 and this started happening when I was 20. I do not get headaches with them. They're just extremely disorienting for 15-30 seconds. I've had my eyes checked recently just for my sight (Which is perfect), but perhaps I need someone to take a closer look.