We are born with a gel within the eye called the vitreous . This sits in the area behind the lens and is adherent to the retina. As we get older the vitreous starts to collapse in on itself as the proteins within it start to clump together, this forms floaters (clumps of proteins within the vitreous). Eventually the vitreous becomes detached from the retina , as it does so the vitreous pulls on the retina and causes small flashes of light. Very occasionally if the vitreous pulls on an area, where it is firmly attached to the retina, it can cause a retinal tear.
Generally floaters are not a problem but more of a nuisance. Most patients get used to them. If necessary they can be removed quite safely, with a vitrectomy. I do not recommend laser for floaters.
Flashing lights usually settle without consequences, but should your flashing lights not settle or become more frequent or are associated with a sudden increase in floaters, you should seek an expert opinion as soon as possible.
If your flashing lights and floaters are followed by a permanent shadow across your vision , that does not move, then you must seek an urgent opinion.