Floaters and Flashes

What are floaters?

By middle age, most people see small specs or clouds moving in their vision. These are called floaters. They can often be seen when looking at a plain background such as a blank wall or blue sky.

Floaters are tiny clumps of gel in the vitreous, the clear jelly-like fluid that fills the inside of your eye. They appear in your vision because they cast a shadow on the retina. They move quickly with eye movement and float away when eye movement stops. They can occur in a variety of different shapes: dots, circles, lines, clouds or cobwebs.

What causes floaters?

As we get older, the vitreous gel starts to thicken and shrink, forming clumps or strands inside the eye. The vitreous may pull away from the back of the eye resulting in a posterior vitreous detachment. This is a common cause of floaters.

Posterior vitreous detachment is more common in patients who:
  • Are short sighted
  • Have undergone cataract surgery
  • Have had YAG laser following cataract surgery
  • Have had inflammation inside the eye

Are floaters serious?

In most cases floaters interfere with vision only slightly. While annoying, they are usually harmless and come and go over the years. In some cases, floaters can interfere severely with vision. Floaters are sometimes caused by bleeding or inflammation in the eye.

What causes flashing lights?

As the vitreous shrinks and comes away from the back of the eye, it can pull on the retina causing some of the retinal cells to fire off. You may see what appears to be flashing lights or lightening streaks. They are usually seen at night or in low light conditions. They may last for a few seconds or several minutes. They can occur off and on for several weeks or months.

Torn retina

When a posterior vitreous detachment occurs, a large floater and multiple flashes are usually seen. In most cases, the large floater disappears over time. Sometimes the vitreous is more firmly attached to the retina and pulls away a piece of the retina as it shrinks. This can cause slight bleeding into the eye which may be seen as a ‘shower’ of new floaters.

When a tear occurs in the retina, the retina can fall off the back of the eye. This is called a retinal detachment and requires an operation to repair it.


Ophthalmic migraine results from spasm of the blood vessels that supply the eye or the visual areas of the brain. Patients may experience flashing lights that appear as jagged lines or ‘heat waves’ often lasting 10-20 minutes. Sometimes this is followed by a migraine headache.

What should you do if you experience floaters or flashes?

Floaters and flashes become more common as we get older. While not all floaters and flashes are serious, you should always have your eyes examined by an ophthalmologist to make sure there has been no damage to your retina. During the examination your pupils will be dilated using eye drops. This may blur your vision so you may need to make arrangements for someone to drive you home after the examination.

Treatment of floaters and flashes

Floaters are usually not harmful. For most people, treatment is not necessary. Large and persistent floaters that interfere with vision can be removed from the eye with an operation called vitrectomy. The vitreous is removed and replaced with a clear salt solution. Because the complications of vitrectomy can be serious, vitrectomy surgery is recommended only in unusual cases. Possible complications include: retinal detachment, cataract formation, glaucoma and loss of vision.

Treatment of flashes

Flashes do not need any treatment if there is no tear of the retina. If a retinal tear is present however, early laser treatment to seal the hole may prevent retinal detachment.
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Suite 15, Mater Medical Centre
76 Willetts Road
Mackay QLD 4740


(07) 4942 3301


(07) 4942 9815
Fig 1. Illustration of floaters.
Image - Floaters
Fig 2. Illustration of flashes.
Image - Flashes


The information provided here is for general education only and should not be construed as individual medical advice. For advice relevant to your particular situation, please speak to Dr Hornsby.