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Posterior Vitreous Separation
When a patient has the symptoms of floating objects or flashing lights in his or her field of vision, and we have determined that there is a posterior vitreous separation, there are some things to watch for: the condition could lead lead to a retinal hole or a wholesale detachment of the retina.
First, let's explain what a posterior vitreous separation is. The eye is composed of a tough outer shell, called the sclera (the white of the eye) and the cornea (the clear covering over the iris). Behind the colored iris is the lens, and behind the lens is a hollow area filled with a 'Jell-o-like' substance. This substance is called the vitreous humor. On an inside surface of this hollow area is the portion of the eye that registers the light and fires off nerve endings that result in an image. When we are born the vitreous humor adheres to the retina.
an example of posterior vitreous separation
As we age, there is a tendency for the vitreous humor to shrink. Eventually it shrinks enough for the attachment between the vitreous humor and the retina to break. This usually happens catastrophically, that is, one second it is attached and the next it has broken. Behind the formed vitreous, the remaining space is filled with a more watery fluid called the unformed vitreous. However it remains attached to the front-most portion of the retina.
Sometimes the separation removes small pieces of connective tissue from the retina and these are perceived as floating objects in the field of vision, other times looking like cobwebs. As the formed vitreous contracts, condensations of protein occur in the substance of the vitreous gel. These also are perceived as floaters. They have no medical significance other than as an annoyance. Sometimes they subside; sometimes they do not (click here to read more about floaters and flashers).
Since the retina has blood vessels on its surface, the contracting gel may create a hole in one of them. This may result in some blood cells escaping into the vitreous humor. These floaters are seen as round floating dots, but can also be seen as dense sheets or veils. These usually disappear in a few days or weeks. If the floaters interfere with vision, they can be removed surgically. However, this can frequently cause more problems than it solves, and we do not usually recommend surgery for the latter condition except in extreme circumstances.
Since the vitreous gel or formed vitreous remains attached to the peripheral retina, it can tug on the retina where it is attached. This causes the nerve endings to fire and these events are seen as light flashes or streaks, usually on the side of one's vision toward the temple. These flashes or streaks tend to diminish with time.
When the vitreous separates it sometimes pulls a larger hole in the retina. If this happens, fluid may undermine the retina and a retinal detachment can follow. This is the most serious complication of a posterior vitreous separation. Some of the symptoms of a developing retinal detachment are:
More than 10 floaters in the field of vision at one time
Escalation of the frequency of flashers
Seeing a dense, dark object enter the field of vision from the sides, top or bottom
A curtain effect across your field of vision, or any sudden change in vision
Should any of these symptoms occur, it is important you get in touch with our office immediately.
We hope this information will be of benefit to you in helping us take care of your most precious asset: your vision.