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Flashes & Floaters & Posterior Vitreous Detachment

A condition that worsens with age


Many people occasionally see some floating material in their vision. This may appear as a dot, a translucent short string, or a "tadpole". These floaters are often seen only under bright lighting circumstances, for example, against snow or a bright sky or a white ceiling. Some patients first notice them when looking through a microscope or binoculars. Most such floaters are visible again under similar lighting conditions. These non-worrisome floaters represent flecks of material floating in a liquid pocket within the vitreous gel-bag in the back of the eye.

Posterior vitreous detachment (PVD) produces another kind of floater, which is moderately worrisome. PVD is a rather common event. About 50% of eyes by age 60 have gone through this process. The sudden appearance of new floaters in one eye is the primary symptom of a PVD. These floaters are usually described as a cobweb, a comma or circle, and usually appear in the vision slightly to the side from where one looks.  Sometimes a PVD is accompanied by flashes of light off to the side in the vision of the affected eye. Occasionally these flashes precede the actual posterior vitreous separation by several days or even weeks. Sometimes they last on an occasional basis for months afterward. Eventually, they subside.

Apart from the nuisance of experiencing new floaters, the problem with a PVD is that about 10% of the time the retina (the “Saran Wrap” thin membrane suctioned up against the inside back part of the eyeball –if your eye was a camera, it would be the film) is torn in the process. About 50 percent of the eyes that have a retinal tear will, if not treated, go on to develop a retinal detachment. If this is going to occur, it usually occurs during the first 6 weeks from the onset of floaters. (See Detached and Torn Retina section)  Suddenly seeing a large number of tiny dots in one's vision, especially along with other floaters and flashes, increases the concern. These dots are either red blood cells or freed retinal cells implying that either a blood vessel on the retina has been tweaked or the retina itself has been torn. The likelihood of finding a retinal tear in the present of these "dots" is about 85%, increased from the 3% to 15% chance when they are not present.  Since almost all of the retinal detachments that result from tears occurring from a PVD develop within 6 weeks of the onset of floaters, it follows that if one has had symptoms of a PVD for more than 6-8 weeks, one has been through the period of major worry of retinal detachment.

A PVD can also cause microtrauma to the surface of the retina causing a scar to form called an epiretinal membrane (see Macular Pucker/Epiretinal Membrane Section) which can distort vision.

Risk factors

While most people see a few spots on occasion, they can occur more frequently and become more noticeable with age when a posterior vitreous detachment occurs. More rare causes of floaters include infection, inflammation, hemorrhage, retinal tears, or eye injury.


Specks and threadlike strands that drift across a person’s field of vision are the floaters. When you try to look at them, they generally float away. Floaters are most visible when looking at bright objects, such as white paper or blue skies. A new floater, flashes, or shower of floaters is worrisome for a PVD and/or retinal tear.  In most eyes, the floaters will "lighten up" over several weeks to many months. In addition, most patients eventually get quite used to the floaters that remain, noticing them only when asked to look for them. (Admittedly, this may not sound very likely right now, but it almost always comes to pass.)  If the floaters are still bothersome after about 6 months, a simply surgery can be performed to remove them permanently.


Flashes and floaters are not generally a serious condition needing treatment, but they can be symptoms of vitreous or retinal detachment.  If one has experienced floaters suggesting a PVD, it is a good idea to be examined by an eye physician within a few days and to avoid heavy jarring exercise in the meantime. The proper examination involves dilating the pupil with eye drops (usually, but not always, both eyes are dilated). The eye is examined with the patient lying down using the indirect ophthalmoscope (which appears as a bright light on the examiner's forehead) and a hand-held lens. A small probe called a scleral depressor is used to press on the eyeball through the eyelid in order to bring into view the part of the retina in which the tears are usually found.  If a tear is not discovered, it is not likely that one will develop later. However, it is not impossible. Symptoms that should cause one to return for re-examination are: A new mess of floaters, especially if accompanied by a large number of little dots or a shade or a shadow covering up or severely disturbing part of the side (or up or down) vision of the affected eye.  It does not hurt to check the peripheral (side) vision briefly on a daily basis, especially during the 6 to 8 week "danger period". This is accomplished by closing the other eye, picking an object to look at on the opposite wall straight ahead, and presenting one's fingers off to the side, and above and below, to make sure that the area of the side vision that you ought to be able to see is still working.

What is Not a Floater

Shimmering lights which obscure a portion of the vision, gradually developing and subsiding over 15 minutes to an hour and usually present to some extent in both eyes (if one thinks to check the other eye) are not floaters. Most commonly these symptoms are related to migraine, even though they sometimes occur without headache.

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