Re: Lightning bolts.
If you do a search for PVD (posterior vitreous detachment) you will find explanations of what happens to the eyes of most people over the age of about 60. This process can cause flashes of light for some people and usually ends with the clean separation of the vitreous from the retina. However, in some cases the separation is not complete so you do need to have regular checkups to make sure. Otherwise, some damage can be caused to the retina.