A Posterior Vitreous Detachment (PVD) occurs when the vitreous gel that fills the inside of the eye pulls away from the retina lining the back of the eye. Occasionally, these detachments can pull the retina and cause a retinal tear or detachment, which is a serious medical emergency that can sometimes cause permanent vision loss.

As we age, the vitreous gel in our eyes becomes more and more acqueous and less gel-like, oftentimes seperating from the retina. This is very common in people over the age of 80 or those who are very nearsighted. Usually as the vitreous pulls away, it can condense into tiny strands that float around in your vision. These spots and strands are known as "floaters" or vitreous syneresis. Floaters are harmless, but can sometimes be annoying. They will eventually sink and settle to the bottom of your eye and out of your line of vision, though this process can take weeks or months.

When the vitreous pulls on the retina, it tends to cause flashes of light to appear in your vision. If you notice a sudden oncoming of flashes, an increase in floaters, or a "spiderweb" or dark curtain in your vision, call your doctor immediately for an eye exam to determine if the retina has detached. If necessary, surgery for a retinal detachment will often be scheduled within 24 hours.