Posterior Vitreous Detachment

(Vitreous Floaters and Posterior Vitreous Detachment [PVD])

The vitreous gel ages along with the rest of our bodies. When we are born, the vitreous is firm just like jello right out of the refrigerator. As with jello, the vitreous has a firmer “skin” or cortical layer surrounding it. As we age, the vitreous liquefies, just like jello sitting out of the refrigerator for a while. This liquefying of the vitreous gel is a process known as syneresis.

As the gel liquefies, small lakes may form within the vitreous that gradually enlarge and join together. The remaining gel collapses in upon itself. When this happens, the “skin” that is adjacent and adherent to the retinal surface separates. This tugs on the retinal surface. The retina is normally stimulated by light and produces a signal sent to the brain that we see as a picture. With the PVD, the retina is being stim¬ulated by mechan¬ical tugging. This traction on the retina is interpreted by the brain as a series of flashing lights. These flashes may be seen at any time, but are more common when enter¬ing a darkened room, or with sudden movements of the eyes or the head.

The floaters may occur when the gel collapses upon itself allowing clumps of more solid gel to float with¬in these lakes. Light that enters into the eye strikes these gel particles producing shadows or floaters. These are more commonly seen in bright light such as looking at the blue sky or while reading against a bright back¬ground. They are not as well seen in dim light such as in a dark room.

Occasional¬ly, the gel may be so tightly attached to the retina that it actually tears the retina and creates a retinal break. Liquid vitreous can then pass underneath the retina producing a retinal detachment producing even more flashes. When the retina tears, it may also bleed into the vit¬reous producing even more floaters. We spend a great deal of time carefully examining the retina to make sure that no breaks were created.

This whole process of a posterior vitreous detach¬ment is a dynamic one with many starts and stops over many weeks or even months. There¬fore, even when we don’t see evidence of a retinal tear or retinal detachment on the first examination, it is very important to reexamine the retina again, partic¬ularly if the flashes increase in quality, frequency or duration, or if there are new floaters.