What is a posterior vitreous detachment?
The vitreous is the gel-like substance that fills the back of the eye. When you are young, this gel is quite firm with a uniform consistency and is adherent to the surface of the retina. As you get older, the gel begins to break down and develop pockets of liquefaction. Within these pockets, the gel proteins clump together which lead to the experience of floaters. In most people, at some point in your life, (usually between the ages of 40 and 60, but earlier for moderately to severely near-sighted persons or people who experience a severe trauma to the eye) there is sufficient breakdown of the gel that it begins to separate from the surface of the retina. If the separation occurs gradually, most patients will be unaware of the changes. If there is a sudden collapse of the gel off the retinal surface light flashes or the sudden onset of floaters can develop. Where the posterior vitreous is attached to the optic nerve at the back of the eye, is a point of more firm attachment, and when this part separates, a ring of condensed vitreous gel which previously had been the site of attachment to the optic nerve, “floats” in the middle cavity or of the eye. Often this ring is seen a gray, white or black doughnut if seen dead on, or as a squiggly line if seen from the side. If the gel does not separate cleanly or pulls too strongly on areas in the peripheral retina or if preexisting weak spots are present in the retina e.g. lattice degeneration, then tears can develop.
How is a posterior vitreous detachment treated?
Patients who experience the sudden onset of flashing lights or floaters may be developing a posterior vitreous detachment. Timely examination with pupil dilation is important to make sure no retinal tear or detachment has developed that requires treatment. Typically, the floaters associated with a new posterior vitreous detachment diminish over several weeks to months and are not harmful even if they don’t go completely away. Without a dilated examination, however, it is not possible to distinguish “innocent” floaters from those associated with tears or detachment.