The middle of our eye is filled with a clear gel called vitreous (vi-tree-us) that is attached to the retina. Sometimes tiny clumps of gel or cells inside the vitreous will cast shadows on the retina, and you may sometimes see small dots, specks, strings or clouds moving in your field of vision. These are called floaters. You can often see them when looking at a plain, light background, like a blank wall or blue sky.
As we get older, the vitreous may shrink and pull on the retina. When this happens, you may notice what look like flashing lights, lightning streaks or the sensation of seeing “stars.” These are called flashes.
Usually, the vitreous moves away from the retina without causing problems. But sometimes the vitreous pulls hard enough to tear the retina in one or more places. Fluid may pass through a retinal tear, lifting the retina off the back of the eye — much as wallpaper can peel off a wall. When the retina is pulled away from the back of the eye like this, it is called a retinal detachment.
The retina does not work when it is detached and vision becomes blurry. A retinal detachment is a very serious problem that almost always causes blindness unless it is treated with detached retina surgery.