As you get older, the vitreous pulls away from the retina causing a posterior vitreous detachment. This normal aging change may cause floaters. While these may be perfectly harmless and of no concern, floaters my also be a sign of a retinal tear or hemorrhage. You should see your ophthalmologist if floaters develop suddenly or if you notice an abundance of new floaters.
Flashing lights or lightning streaks can also occur when the vitreous gel pulls on the retina. Flashing lights can appear off and on for several weeks or months. Again, this is a normal process that often occurs with aging. While in most cases no damage occurs to the underlying retina, in about 10% of cases a retinal tear may be caused. Therefore, if you notice a sudden appearance of flashes, you should notify your ophthalmologist immediately.