June 5, 2007 at 7:09 PM CDT - Updated July 26 at 9:05 AM
There may be areas where the vitreous is very strongly attached to the retina, usually in the peripheral retina. If the vitreous pulls away from the retina in an area where the retina is weak, the retina may tear. Imagine a piece of adhesive tape attached to tissue paper. If you try to pull the tape off the tissue paper, you will tear the paper. A tear of the retina works very much the same way. If the retina tears across a retinal blood vessel, blood will enter the vitreous. This is called a vitreous hemorrhage.