There may be areas where the vitreous is very strongly attached
to the retina. If the vitreous pulls away from the retina in an
area where the retina is weak, the retina may tear. One
condition that weakens the retina is called lattice degeneration.
When lattice degeneration is present, it indicates that the
retina is thin and may be more susceptible to tear of the retina
than in an area without lattice degeneration. Imagine a piece of
scotch tape attached to tissue paper. If you try to pull the
scotch tape off the tissue paper, you will tear the paper. A
tear of retina works very much the same way. If the vitreous is
firmly attached, as it pulls away, it can tear the retina. If
the retina tears across a retinal blood vessel, there will be
bleeding into the vitreous. This is called a vitreous
When there is a little bleeding, red blood cells floating and
moving in the vitreous create the sensation of walking through a
swarm of flies. If even more bleeding occurs in the vitreous, it
looks like a spiderweb or a swirling mass of black or red lines.
If there is a great deal of bleeding into the vitreous cavity,
vision may be reduced significantly, or even become very dark.
When a retinal tear occurs, it is a potentially serious problem.
If a vitreous hemorrhage also occurs, it is even more serious.
The retina can tear immediately following a posterior vitreous
detachment (PVD), or weeks later. If no tear has developed
within eight weeks after a PVD, the retina probably will not
Any pateint who experiences sudden or new floaters, or flashing
lights of any kind, should have a complete retinal examination
immediately. These symptoms may indicate that a retinal tear
has occurred. A retinal tear may result in a retinal detachment.
Since retinal tears and retinal detachments begin in the
peripheral retina, your doctor may suggest that you test your
peripheral vision to be sure there are no changes.
Testing Peripheral Vision
You have just completed testing the peripheral vision of each
eye. If you notice any peripheral vision loss, or any visual
changes, distortion, or blur that was not present the day before,
notify your eye doctor immediately.
- Cover your left eye with the palm of your hand and look at
your right eye in a mirror.
- While you are looking at your eye in the mirror, and without
moving your eye up or down or from side to side, be sure that you
can see all four corners and sides of the mirror.
- Now, cover your other eye and perform the same test.