The vitreous is the large gel like substance which fills up most of the eye. As light passes through the vitreous it is sometimes distorted by inconsistencies in the vitreous substance which causes little gray shadows across our field of vision. These are called floaters . They are more notable when looking at a bright area like the sky or computer screen. In most cases, they are not serious, but new floaters sometimes maybe significant sign of problems.
In a young person, the vitreous has a gel -like structure but as we age it becomes less solid and more liquid like. Eventually it may not be able to holds its shape and collapses on itself. This is called a posterior vitreous detachment (PVD) and is a very common event in middle age or older people. It most often causes a new large floater which can be irritating but not a problem. However sometimes when it pulls away from the retina it tears the retina which can lead to a retinal detachment and severe vision loss. Retinal tears are treated with laser surgery.
Prior to detaching from the retina, the traction of the collapsing vitreous can lead to retinal problems such as a macula hole or macular wrinkle . Macular holes are usually treated with surgery while macular wrinkles may or may not need surgery.