For most people, the cause of eye floaters and flashes is age-related. As you get older, the vitreous gel that fills the inside of the eyeball can liquefy and separate from the retina. Small, momentary flashes of light are commonly experienced during vitreous separation. The vitreous pulls on the retina which makes you think you are seeing a light, but it is actually caused by movement of the retina. Sometime the flashes persist for a few months until the vitreous is finished separating. Rarely flashes are associated with a tear in the retina. Another cause of flashes are acephalgic (without pain) migraines.
Floaters are small specks or strands in the vitreous gel that move into your field of vision. The floaters present in different shapes very similar to small dots, circles, clouds, lines and even cobwebs. Floaters move as your eyes move; if you try to look at them directly, they may seem to dart away.
The primary difference between flashes and floaters is that floaters are usually seen during daylight or in lightened areas, whereas flashes are typically noticed at night or in a dark room.
Factors that can increase your risk of floaters include:
Flashes and floaters are generally harmless, but should they suddenly appear, it is important to seek the services of a specialist in order to rule out a serious cause such as bleeding in the eye (more common with diabetes) or a retinal tear or detachment. A retinal detachment requires surgery and can lead to permanent vision loss if left untreated.