Detached and Torn Retina
A retinal detachment is a very serious problem that almost always causes blindness unless treated. The appearance of flashing lights with floating objects, or a gray curtain moving across the field of vision can all be indications of a retinal detachment. if any of these occur, see an ophthalmologist right away.
As one gets older, the vitreous, the clear gel-like substance that fills the inside of the eye, tends to shrink slightly and take on a more watery consistency. Sometimes as the vitreous shrinks it exerts enough force on the retina to make it tear.