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Information on Posterior Vitreous Detachment, Floaters & Flashes

Sep 07, 2015 - 0 comments

Posterior Vitreous Detachment



A vitreous detachment is a normal part of aging. By age 50 about half the population has a vitreous detachment (also know as a posterior vitreous detachment or PVD) and by age 70 the figure is about 75 %. The back of the eye is filled with a substance called the vitreous gel. It is very similar to clear Jello. When Jello is made in a mold and put in the refrigerator it becomes a firm gel. If Jello is set on a plate and left for a week or more at room temperature it turns back into a liquid and the Jello collapses into a watery mixture of liquid and gel. In like fashion as we age the firm vitreous of our youth softens and liquefies as we age. When this happens the vitreous strips off the retina. The retina is the sight forming layer of the eye (like the film in a camera). A membrane connects the vitreous to the retina. Usually it peels off smoothly and does so spontaneously without trauma. In some cases if the vitreous is liquefied in the center and there is trauma such as an automobile accident, a blow to the eye, a bad fall this can cause a PVD. Pieces of the membrane fall into the center of the eye and "float" around--hence the name 'floaters'. Usually there are several large or moderate floaters.
While these floaters are annoying and distracting they are not a serious problem in most cases. Most floaters will settle down to the bottom of the eye and are no longer seen over a period of days, weeks or months. Alternately they may drift to the front of the eye making them less conspicuous, or the brain simply tunes them out and they are not noticed. There is no cure for floaters, no medication or eye drop to make them go away. Laser treatment to break them up has not proved useful and an operation called a vitrectomy to remove the floaters is far too risky to do for routine floaters.

As the vitreous strips off the retina in some cases it will "snag" the retina and jerk on it. The retina responds to pressure with a flash of light. Because the retina is so much more sensitive to light (and pressure) when dark adapted the floaters are usually seen at night and in the dark. Because inertia causes a tug on the retina the flashes often occur with head or eye movements. In most cases the flashes will stop over a few days to several weeks.

In a very very small number of people the vitreous that has snagged the retina can tear it. A retinal tear can lead to bleeding in the eye and/or a retinal detachment. A retina detachment is a very rare problem that may occur in 1 in 5000-7000 people that have not had cataract surgery. A retinal detachment can cause loss of sight and needs surgical correction. Retinal detachment is more common in people that have had cataract surgery (perhaps 1 in 2000 to 3000), those that are severely near-sighted (myopic), have a family history of retinal detachment or in eyes with severe trauma.   Dilation of the pupils with eye drops does not cause floaters nor any type of food.

In my practice I do not limit the activity of my patients who have only floaters and in whom I have checked the vitreous and retina (as has your ophthalmologist). If they have flashes I ask they avoid heavy bending, stooping, lifting and "jarrying" activities. If the flashes worsen, start to occur in the daytime or without eye movement, of if a sudden increase of small black floaters occur (like a handful of soot dropped from the top of the eye--that is what blood in the eye often looks like) or if the flashes persist greater than one week they return for retinal re-examination. Once the flashes stop regular activities can be resumed.

Also to belabor the obvious, both eyes are the same age. When a PVD occurs in one eye it will invariably occur in the other eye sooner or later (sometimes years later). When this happens they eye should be examined and the same recommendations apply again to the other eye.

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