The vitreous humor fills the eye behind the lens. At birth it is attached to the retina. Over time the vitreous changes, shrinking and developing pockets of liquefaction, similar to the way a gelatin dessert shrinks, or detaches, from the edge of a pan over time. At some stage the vitreous may peel away from the retina. This is usually a sudden event. When this occurs there is a characteristic pattern of symptoms :
As a posterior vitreous detachment proceeds, adherent vitreous may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with resultant flashes. The risk of retinal detachment is greatest in the first 6 weeks following a vitreous detachment, but can occur over 3 months after the event.