You’re sitting there, minding your own business, when all of a sudden, a lightning flash appears out of the corner of your eye. Or maybe a bunch of gnats or spiderwebs appear in the periphery of your vision. You try to swat them away but nothing is there. You’ve most likely just had a posterior vitreous detachment.
WHAT IS POSTERIOR VITREOUS DETACHMENT?
Think of the eye as a hollow ball. The center cavity of the eye is filled with a substance called the vitreous. It has a gel-like consistency similar to raw egg whites, neither solid or liquid. As we age, the vitreous degenerates and forms small pockets of liquid inside the gel. There comes a point where the pockets of liquid come together and break through behind the vitreous gel causing it to pull away from the retina in the back of the eye. As this occurs, the vitreous tears away small pieces of tissue from the optic nerve (Fig. 1 A). This does not harm the optic nerve, but these small pieces of tissue float on the back of the vitreous, casting a shadow on the retina. You see these as floaters. As the vitreous sloshes around in the eye, you see the floaters moving around in your peripheral vision. It is very common and will occur in virtually everybody as age catches up. Most of the time, it occurs without causing any acute or long-term visual problems.
PVD is a natural change that occurs with age. PVD happens in over 75% of those aged 65 or over. It is important to remember that PVD is not an ocular disease in itself, but can lead to a very serious eye problem (retinal detachment).
PVD Figure 1.
WHAT ABOUT THE FLASHES?
The flashing lights you see from PVD are typically brief white or golden yellow streaks in the periphery of your vision. They are more obvious in the dark, and can be brought on by moving your eyes. The only message that the retina can send back to the brain is light. It cannot feel pressure, either pushing or pulling. As the vitreous pulls away from the retina, your brain detects this as light (Fig 1 B). When you see a flash of light, your vitreous is tugging on your retina.
WHAT COMPLICATIONS CAN YOU GET?
In the great majority of cases, the vitreous detaches without causing any problems. However, in up to 10%, vitreous detachment is accompanied by an ocular complication. The main complications are vitreous hemorrhage, retinal tear and retinal detachment
Vitreous hemorrhage: Sometimes, when the vitreous pulls away, it can tear a small blood vessel. The amount of bleeding can be mild (you see what looks like a 4th of July sparkler) or severe (your vision becomes completely clouded). If you have vitreous hemorrhage, your eye needs to be examined thoroughly for any signs of retinal tear or retinal detachment. That means getting your pupils dilated. If there is too much blood to see the retina, an ultrasound scan will need to be done. Usually the blood will clear over several months. Severe cases of bleeding will require surgery to remove the blood.
Retinal tear: Sometimes as the vitreous detaches, it tugs on the retina and causes the retina to tear or break. This is more likely if there are areas of weakness in your retina. This is the reason why you need a dilated exam if you develop symptoms. If the retina is torn, it needs to be sealed off with a laser to prevent a retinal detachment.
Retinal detachment: A retinal detachment occurs when fluid goes through the retinal tear and peels the retina away from the wall of the eye, much like when wallpaper peels away from the living room wall. You might see a shadow or curtain blocking your vision. This is a sight-threatening condition and in most cases, will require retinal detachment surgery to restore vision.
It is not really possible to predict if you will develop problems as your vitreous detaches. What is known is that you are at higher risk of PVD-related complications if you have:
– A retinal tear or detachment in the other eye
– A family history of retinal tears or detachment
– Genetic disease such as Marfan’s syndrome and Stickler syndrome
– High nearsightedness
DO YOU NEED TO TREAT POSTERIOR VITREOUS DETACHMENT?
For most people, no treatment is required. The detached vitreous remains detached and does not re-attach again. PVD does not cause any permanent loss of vision. But a retinal detachment will. It is therefore very important that you consult your ophthalmologist as early as possible for a thorough dilated retinal examination if you experience the symptoms of flashes and floaters.
The flashes and floaters will eventually settle over several weeks to several months. Flashing lights tend to settle completely because the vitreous is no longer tugging on the retina.
Floaters will become less noticeable as your brain learns to adapt and to ignore them. However, they are unlikely to disappear completely. If you have a very annoying floater in the center of your vision, you may be able to displace it moving your eyes in a gentle circular motion. In some severe cases, a vitrectomy surgery may be appropriate. You may notice new floaters when new pockets of the vitreous degenerates. Don’t worry about these if you notice a few new floaters. If you notice a new shower of floaters, consult your ophthalmologist as soon as possible for a repeat retinal examination.