Eye Floaters, Flashes and Spots
Eye floaters are those tiny spots, specks, flecks and "cobwebs" that drift aimlessly around in your field of vision. While annoying, ordinary eye floaters and spots are very common and usually aren't cause for alarm.
Floaters and spots typically appear when tiny pieces of the eye's gel-like vitreous break loose within the inner back portion of the eye.
When we are born and throughout our youth, the vitreous has a gel-like consistency. But as we age, the vitreous begins to dissolve and liquefy to create a watery center.
Some undissolved gel particles occasionally will float around in the more liquid center of the vitreous. These particles can take on many shapes and sizes to become what we refer to as "floaters."
You'll notice that these types of spots and floaters are particularly pronounced when you peer at a bright, clear sky or a white computer screen. But you can't actually see tiny bits of debris floating loose within your eye. Instead, shadows from these floaters are cast on the retina as light passes through the eye, and those shadows are what you see.
You'll also notice that these specks never seem to stay still when you try to focus on them. Floaters and spots move when your eye moves, creating the impression that they are "drifting."
When Are Eye Floaters and Flashes a Medical Emergency?
If you see a shower of floaters and spots, sometimes accompanied by light flashes, you should seek medical attention immediately.
Clumps occur when the vitreous gel begins to liquefy or shrink, usually with aging, and detaches from the retina.
For some people, floaters are clumpy; for others, they're stringy. They may be light or dark. What you see is actually the shadows cast by clumps of vitreous gel when light shines past them onto the retina. (If you can't see the image, you may need Flash Player.)
The sudden appearance of these symptoms could mean that the vitreous is pulling away from your retina or that the retina itself is becoming dislodged from the inner back of the eye that contains blood, nutrients and oxygen vital to healthy function. When the retina is torn, vitreous can invade the opening and push out the retina leading to a detachment.
A study reported in the Journal of the American Medical Association in late 2009 found that sudden presence of eye floaters and flashes means that one in seven people with these symptoms will have a retinal tear or detachment. And up to 50 percent of people with a retinal tear will have a subsequent detachment.
In cases of retinal tear or detachment, action must be taken as soon as possible so that an eye surgeon can reattach the retina and restore function before vision is lost permanently.
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Posterior vitreous detachments (PVDs) are far more common than retinal detachments and often are not an emergency even when floaters appear suddenly. But some vitreous detachments also can damage the retina by tugging on it, leading to a tear or detachment.
Light flashes known as photopsia can occur when your retina receives non-visual (mechanical) stimulation, which can happen when it is being tugged, torn or detached.
What Causes Eye Floaters and Spots?
As mentioned above, posterior vitreous detachments or PVDs are common causes of vitreous floaters. Far less commonly, these symptoms can be associated with retinal tears or detachments that may be linked to PVDs.
But what leads to vitreous detachments in the first place?
As the vitreous gel fills the inside of the back of the eye, it presses against and actually attaches to the retina. Over time, the vitreous becomes more liquefied in the center. This sometimes means that the central, more watery vitreous cannot support the weight of the heavier, more peripheral vitreous gel.
Vitreous gel then collapses into the central, liquefied vitreous. While this occurs, the peripheral vitreous detaches from the inner back of the eye where the retina is located.
Eye floaters resulting from a vitreous detachment are then concentrated in the more liquid vitreous found in the interior center of the eye.
More than half of all people by the time they are 80 will have had a vitreous detachment.* If you are among the 40 percent of people with PVDs who also experience light flashes, then you have about a 15 percent chance of also developing a retinal tear.**
Light flashes during this process mean that traction is being applied to your retina while the PVD takes place. Once the vitreous finally detaches and pressure on the retina is eased, the light flashes should gradually subside.
What Causes Eye Flashes?
Ordinarily, light entering your eye stimulates the retina. This produces an electrical impulse, which the optic nerve transmits to the brain. The brain then interprets this impulse as light or some type of image.
If the retina is mechanically stimulated (physically touched), a similar electrical impulse is sent to the brain. This impulse is then interpreted as a "flicker" of light.
When the retina is tugged, torn or detached from the back of the eye, a flash or flicker of light commonly is noticed. Depending on the extent of the tear or detachment, these flashes of light might be short-lived or continue indefinitely until the retina is repaired.
Flashes (photopsia) also may occur after a blow to the head, often called "seeing stars."
Some people experience flashes of light that appear as jagged lines or "heat waves" in both eyes, often lasting 10-20 minutes. These types of flashes are usually caused by a spasm of blood vessels in the brain, which is called a migraine.
If a headache follows the flashes, it is called a migraine headache. However, jagged lines or "heat waves" can occur without a headache. In this case, the light flashes are called an ophthalmic migraine, or a migraine without a headache.
Photopsia also can be a symptom of digitalis toxicity, which can occur particularly in older people who take digitalis or related drugs for heart problems.
Other Conditions Associated With Eye Floaters and Flashes
Studies show that bleeding (vitreous hemorrhage) accompanying a PVD means exceptional traction has occurred, which increases the possibility of a retinal tear or detachment. Traction exerted on the retina during a PVD also can lead to development of conditions such as macular holes or puckers.
Vitreous detachments with accompanying vitreous floaters also may occur in circumstances such as:
- Inflammation in the eye's interior
- Cataract surgery
- YAG laser eye surgery
- Diabetes (diabetic vitreopathy)
- CMV retinitis
Inflammation associated with many conditions such as eye infections can cause the vitreous to liquefy, leading to a PVD.
When you are nearsighted, your eye's elongated shape also can increase the likelihood of a PVD and accompanying traction on the retina. In fact, nearsighted people are more likely to have PVDs at a younger age.
PVDs are very common following cataract surgery and a follow-up procedure called a YAG laser capsulotomy. The laser treats a cataract surgery complication in which cloudiness develops in the capsule underlying the artificial lens (IOL). Eye procedures such as these can increase trauma within the eye, leading to vitreous detachments.
Treatment for Spots and Floaters
Most eye floaters and spots are harmless and merely annoying. Many will fade over time and become less bothersome.
Sometimes people are interested in surgery to remove floaters, but doctors are willing to perform such surgery only in rare instances when vision seriously is hampered.
At this time, the only way to "clear" the vitreous and its specks and webs would be to remove the gel-like substance entirely from the eye through a vitrectomy procedure. Usually, the vitreous then is replaced with a saline liquid.
Remember that the sudden appearance of a significant number of floaters, especially if they are accompanied by flashes of light or other vision disturbances, could indicate a detached retina or other serious problem in the eye. A retinal detachment or tear is an emergency, requiring immediate attention.
If you suddenly see new floaters, visit your eye doctor without delay.
**Not just a PVD: differential diagnosis of flashing lights. Retinal Physician. November 2007.
Incidence of posterior vitreous detachment after cataract surgery. Journal of Cataract and Refractive Surgery. June 2009.
[Page updated October 2012]
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