A posterior vitreous detachment (PVD) is an ocular condition in which there is a separation of the vitreous humor from the retina.
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 can be, and usually is, a sudden event. When this occurs there is a characteristic pattern of symptoms:
Flashes of light (photopsia) - very brief in the extreme temporal (outside away from the nose) part of vision
A sudden dramatic increase in the number of floaters
A ring of floaters or hairs just to the temporal side of the central vision
A slight feeling of heaviness in the eye sometimes accompanied by slight nausea similar to very mild shock
When a posterior vitreous detachment occurs, there is also the possibility of a tear in the retina. If this happens, it increases the risk of retinal detachment. This can be caused by the vitreous fluid seeping under the tear and creating pressure between the retina and the back of the eye. Also, a firmly-adhered vitreous can create traction on the retina, tearing it. After the initial PVD event, the chance for retinal detachment happening lessens over time but can occur for about 3 months after the event.
Prompt examination of patients experiencing vitreous floaters combined with expeditious treatment of any retinal tears has been suggested as the most effective means of preventing certain types of retinal detachments.