Flashes and Floaters

floatersWhat are Eye Floaters?

You may sometimes see small specks, lines or clouds moving in your field of vision. These are referred to as floaters. They can appear as different shapes, such as little dots, circles, lines, clouds or cobwebs. You can often see them when looking at a plain background, like a blank wall or a blue sky.

Floaters are actually tiny clumps of gel or cells inside the vitreous (the clear gel-like fluid that fills the inside of the back of the eye).

Although floaters appear to be in front of the eye, they are actually floating in the vitreous fluid inside the eye. You actually see the shadows that the floaters cast on the retina. The retina is the layer of cells (nerve tissue) lining the back of the eye that senses light and allows you to see.

Video: Floaters

This video demonstrates from a patient’s perspective how floaters may appear and explains the most common cause.

What Causes Floaters?

With normal aging, the vitreous gel starts to change consistency and shrink, forming clumps or strands inside the eye. The vitreous gel pulls away from the back wall of the eye, causing a posterior vitreous detachment or PVD. This is a common cause of floaters.

PVDs are more common in people who:

  • Are nearsighted
  • Have undergone ocular surgery
  • Have had YAG laser surgery of the eye
  • Have had inflammation inside the eye
  • Are over 30 years old

The appearance of floaters may be alarming, especially if they develop suddenly. You should contact Dr. Callahan right away if you develop new floaters.

Are Floaters Ever Serious?

Yes! Floaters may be the very earliest sign of a retinal detachment. As the shrinking vitreous gel pulls away from the wall of the eye, it can cause a tear or hole in the retina. This sometimes causes a small amount of bleeding in the eye that may appear as new floaters. If a retinal tear is not treated, the retina may detach from the back of the eye—a retinal detachment .

Retinal detachment may be prevented by early detection and treatment of retinal tears–generally with a laser to prevent fluid from leaking under the retina. Retinal detachment can cause a permanent decrease or loss of vision. The only treatment for a detached retina is surgery.

You should contact Dr. Callahan as soon as possible if you notice any of the following:

  • An increase in floaters
  • Flashing lights that don’t go away
  • A curtain or veil that blacks or grays out part of your vision
  • An overall change in your vision
Can Floaters Be Removed?

Most floaters are harmless and fade over time or become less bothersome, requiring no treatment. The floaters either settle to the bottom of the eye, out of the central visual axis, or your brain just learns to ignore them. You may notice your floaters more or less under different lighting conditions since you are actually seeing the shadow of the floater on the retina. Surgery to remove floaters is almost never required.

Even if you have had floaters for years, you should schedule an eye examination with Dr. Callahan if you suddenly notice new ones.

What Causes Flashing Lights?

When the vitreous gel rubs or pulls on the retina, you may see what look like flashing lights or lightning streaks. The vitreous stimulates the photoreceptor cells in the retina that allow you to see light. When this occurs, it initiates the same chemical reactions that happen when you see real lights—your brain cannot tell the difference.

You may have experienced this same sensation if you have ever been hit in the eye and seen “stars.” The flashes of light can appear off and on for several weeks or months. As we grow older, it is more common to experience flashes. If you notice the sudden appearance of light flashes, you should contact Dr. Callahan immediately in case the retina has been torn.


Some people experience flashes of light that appear as jagged lines or “heat waves” in both eyes, often lasting ten to 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 visual changes are called ocular migraine, or migraine without headache. Contact Dr. Callahan if you experience these symptoms.

How Are Your Eyes Examined?

In order to evaluate flashes and/or floaters, a careful medical eye examination is necessary. Your pupils must be dilated (enlarged) with eye drops for this examination. Dilation generally lasts several hours and mostly affects your near vision.

During this painless examination, Dr. Callahan will carefully observe areas of your eye, including the entire retina and vitreous. Please note that if your eyes have been dilated, you may need to make arrangements for someone to drive you home afterward.

Floaters and flashes of light become more common as we grow older. While not all floaters and flashes are serious, you should always have a medical eye examination by Dr. Callahan to make sure there has been no damage to your retina.