Posterior Vitreous Detachment

Flashes and floaters are symptoms of a PVD

Dan Carver, O.D., F.A.A.O. • Sep. 2, 2011 6:30 PM

 

 What is the Vitreous?

The vitreous humor is the gelatinous substance that fills two-thirds of the eye’s volume. It is made up of about 98% water and has a “framework” of collagen fibers. Additionally, the vitreous contains hyaluronic acid, the substance found in the synovial fluid of our joints. The vitreous acts as a natural shock absorber. It undergoes structural change with normal aging.

 What is a Vitreous Detachment?

The vitreous doesn’t just sit in the eye. It is actually attached in the front part (anteriorly) where the back of the iris joins the retina. The vitreous is extremely adherent at this point throughout life. There are  often sticky points of attachment to the peripheral retina surrounding this area. The vitreous is also attached in the back part of the eye (posteriorly) to the optic nerve and adjacent central retina called the macula. With normal aging, the vitreous contracts. Tractional forces eventually pull the posterior insertion away from the face of the optic nerve. This is a posterior vitreous detachment or PVD. Most PVDs happen spontaneously. Blunt force trauma can make the vitreous tear away prematurely. This can happen from blows to the eye or head.

Signs and Symptoms

The main symptom of a PVD is a sudden onset of visual "debris" from the attachment material now released to come forward. As the eye moves to fixate on this debris, it moves or "floats" in the visual field. Patients often report a mobile cobweb or spots or threads in their vision. Commonly, a large circular floater is apparent. Floaters are seen most easily by looking at a bright, uniform surface like the ceiling, a wall, or the sky. Ancient Greeks called floaters, muscae volitantes or “flitting flies”. The perception of floaters is referred to as myodesopsia.

Light flashes often accompany floaters when the vitreous tugs on peripheral retinal traction points in the front of the eye. They are a more ominous sign and should not be disregarded. Light flashes are most often seen with sudden head movement particularly in dark conditions such as turning over in bed or moving from bed to the bathroom in the middle of the night. Most PVDs, while annoying, are harmless. Occasionally, however, traction results in a tear in the peripheral retina. A tear left untreated can lead to a sight-threatening retinal detachment. Prompt dilated retinal examination is vital when symptoms of a PVD occur. Throughout life, most people develop common floaters without having a PVD. It is also often said that if you live long enough, you will experience a PVD.

How is a Vitreous Detachment Treated?

Unfortunately, there is no completely safe or easy treatment for a common posterior vitreous detachment. A vitrectomy, an invasive surgery designed to remove the vitreous, is generally considered too risky to perform routinely to eliminate floaters from a PVD. In time, the vitreous sags and floaters often move out of central vision. At the same time, we become less aware of their presence through brain adaptation. A repeat dilation should be performed in 30 days. If new floaters or flashes begin to develop, it is vital to return to our office immediately for examination to rule out a fresh tear or retinal detachment.                                                                                   

 

 


Categories: Patient Care