Posterior vitreous detachment (PVD) is a common condition usually caused by aging. The vitreous, which lies against the retina, is the jelly-like substance that fills the center of the eye. Made mostly of water, the vitreous fluid gives the eye its shape. As we get older, the composition of the vitreous changes, becoming less firm. This change sometimes causes the vitreous to pull on the retina. If the force of the pulling becomes strong enough, the vitreous may actually separate from the retina. This common condition is called a posterior vitreous detachment, as it normally occurs at the back (posterior) of the eye.
Why the Vitreous Detaches:
In children, the vitreous has a consistency similar to that of an egg white. As we age, the center of the vitreous becomes more watery, causing the outer edges to shrink and peel away from the retina. If this shrinking process occurs suddenly, it is called a posterior vitreous detachment. PVD is usually not a big concern or threat to vision, but as complications can occur, an eye doctor should always evaluate the condition.
Symptoms of PVD:
PVD sometimes happens with no symptoms. For some people, however, the experience can be quite alarming. Some people may notice flashes of light or floaters.
- Flashes: Flashes of light may occur as the vitrous pulls on the retina because the brain interprets all signals from the retina as light. The flashes usually last for a couple of weeks and then go away, causing no threat to vision.
- Floaters: Small particles of pigment may break off of the retina, appearing as spots or strings in the vision. The brain will usually adapt to large or stubborn floaters over time, making them less annoying.
Occasionally, a posterior vitreous detachment may cause the retina to tear. Retinal tears are very serious because the vitreous liquid may leak into the tear and build up underneath the retina. If the fluid build-up becomes big enough, the retina may completely separate from the wall of the eye. This condition is known as a retinal detachment and must be treated.
Detection and Diagnosis:
If you experience a sudden onset of flashes and floaters, you may be experiencing a posterior vitreous detachment and need to be examined by an eye doctor. The doctor will most likely dilate your eyes and carefully check for possible tears in the retina. If retinal tears are discovered, your doctor will need to seal them to prevent a retinal detachment. Sealing retinal tears is usually accomplished by laser or freezing treatment.
What You Need to Know:
In most cases of posterior retinal detachment, no signs of retinal damage are found and vision remains the same. Flashes and floaters in your vision will probably improve over time. However, you will need to see your doctor immediately if the flashes and floaters suddenly increase or if you see a black curtain falling across your vision. These are warning signs of a detaching retina and must be treated immediately to preserve vision.
Source: David Kinshuck, A Posterior Retinal Detachment (PVD). Eye Department, Good Hope Hospital NHS Trust. 9 Sep 2007.