Flashes are bright points of light that literally flash into the field of vision when the eyelids are open  or closed.  They usually appear as tiny dashes forming either an oval or a circle.  Flashes come and go in an instant and normally occur in only one eye at a time.  They can indicate vitreous detachment or a serious eye disorder. Both flashes and floaters can be harmless symptoms of aging eyes, or they can be indicators of a serious eye disorder such as a torn retina. Therefore, if you experience new symptoms, you should consult Ophthalmologist...