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Flashing lights and floaters
(posterior vitreous detachment)

Flashing lights and floaters are caused by changes in the jelly of the eye. They may be experienced by up to 75% of people over the age of 65. The main cavity of the eyeball is filled with a jelly-like substance called the vitreous. Throughout life it fills the eye pressing up against the retina which lines the inside of the eyeball. (The retina is the camera film of the eye).

cross-section of the eye

With age the vitreous changes from being jelly-like to being more liquid and at the same time develops opacities within it. These changes in the vitreous cause the visual symptoms of seeing floaters which appear as small particles or as larger shapes often described as like flies or spiders which move around when the eye is moved. As these changes in the jelly happen the vitreous may move away from the retina and may even pull on it causing the symptoms of flashing lights. These symptoms are very common and although they are irritating, they are not usually serious.

The reason you have been examined carefully is because sometimes this process can lead to detachment of the retina. This is when the retina comes away from the wall of the eye leading to loss of vision requiring urgent surgery. If a hole or tear is not found at your examination, no treatment is required and there is no need for you to worry.

The floaters may last for several months but should settle and you will notice them less with time. Treatment is very rarely recommended for posterior vitreous detachment because the risks of surgery outweigh the potential benefits. In rare cases causing severe symptoms, the vitreous can be surgically removed or laser treatment can be performed to disperse the floater.

In the large majority of patients no further problems arise, but you should be seen by an eye doctor without delay if you notice any of the following symptoms:

  1. You notice a sudden rush of floaters
  2. You notice more flashing lights
  3. A dark shadow appears in your vision
  4. A sudden change in or loss of vision occurs

If you have any questions regarding this information, please ask your eye doctor.


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