Most of the eye's interior is filled with vitreous jelly, which helps the eye maintain a round shape. The vitreous is attached to a thin layer of light-sensitive tissue at the back of the eye (retina) by millions of tiny, fine fibres. As we age, the vitreous slowly shrinks, and these fine fibers pull on the retinal surface. Usually the fibers break, allowing the vitreous to separate and shrink from the retina. In most cases, a vitreous detachment, also known as a posterior vitreous detachment, is a natural occurring event as we age and is not sight-threatening and requires no treatment.
As the vitreous jelly shrinks it becomes somewhat stringy and the string strands can cast shadows on the retina, which causes patients to see "floaters." Floaters may also be accompanied by "flashes of light" in the peripheral vision. A vitreous detachment does not threaten vision but it can contribute to diagnoses such as macular holes, retinal tears and retinal detachments that do threaten vision. Those who experience a sudden increase in floaters or an increase in flashes of light in peripheral vision should have an ophthalmologist examine their eyes as soon as possible.