Floaters, Spots and Flashes

What are floaters 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 centre.

Eye floaters can be clumpy or stringy; light or dark. They are caused by clumps or specks of undissolved vitreous gel material floating in the dissolved gel-like fluid (vitreous) in the back of the eye, which cast shadows on the retina when light enters the eye. Click on the image to see floaters in action.

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 “eye floaters.”

You’ll notice that these spots and eye floaters are particularly pronounced if you gaze at a clear or overcast sky or a computer screen with a white or light-coloured background. You won’t actually be able to 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 tiny 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 and the vitreous gel inside the eye moves, creating the impression that they are “drifting.”

When should you seek an assessment from us?

Noticing a few floaters from time to time is not a cause for concern. However, if you see a shower of floaters and spots, especially if they are accompanied by flashes of light, you should seek an opinion from us.

The sudden appearance of these symptoms could mean that the vitreous is pulling away from your retina — a condition called posterior vitreous detachment — or that the retina itself is becoming dislodged from the inner lining of the back of the eye that contains blood, nutrients and oxygen vital to healthy function. As the vitreous gel tugs on the delicate retina, it might cause a small tear or hole in it. When the retina is torn, vitreous can enter the opening and push the retina farther away from the inner lining of the back of the eye — leading to a retinal detachment.

Floaters become more mobile and visible as the vitreous liquefies with age and separates from the retina.

A recent study published in Ophthalmology showed that, among people who experienced the sudden symptom of eye floaters and/or flashes of light, 39.7 percent had a posterior vitreous detachment and 8.9 percent had a torn retina. Other research has shown that up to 50 percent of people with a retinal tear will subsequently develop a detachment of the retina, which could lead to significant vision loss.

In cases of retinal tear or detachment, treatment must occur as soon as possible so that an eye surgeon can reattach the retina and restore function before vision is lost permanently.

• Posterior vitreous detachments (PVDs) are far more common than retinal detachments and often are not an emergency even when floaters appear suddenly. 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. These light flashes may appear as lightning bolts, flickering lights or random sparks.

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 or tugged), 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 traction, tear or detachment, these flashes of light might be short-lived or continue indefinitely until the retina is repaired.

Flashes (photopsias) also may occur after a blow to the head that is capable of shaking the vitreous gel inside the eye. When this occurs, the phenomenon sometimes is 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.

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.

Flashes associated with floaters require an assessment by us to ensure your retinal health.