Eye floaters are caused by moving particles that float in the vitreous humour – the gel-like fluid in the centre of the eye. They appear in your field of vision in all sorts of shapes and sizes: long strands, large spots or smaller dots. In most cases it’s normal and completely harmless. To understand more, let’s look in more detail at what causes eye floaters and spots.

Woman's eye looking into camera: what causes eye floaters?The vitreous humour

In the middle of the eyeball is a fluid with the consistency of jelly. This is called the vitreous humour. As we age, the consistency of the vitreous humour changes and becomes more watery, as small particles of the gel break off and dissolve. Some of these small pieces remain undissolved and cast shadows on the retina as they drift around. The shadows are what we see when we experience eye floaters.

Who is affected by floaters and spots?

While most people will experience these at some time, others are more susceptible:

  • People with posterior vitreous detachment (PVD), where the vitreous humour detaches from the retina. This is very common and will affect around half of all over-50s.
  • Those who have undergone cataract surgery.
  • Those with an eye infection or injury.
  • Older people.

Should I be worried?

Probably not. The breaking down of the vitreous humour is normal and it is extremely common to experience floaters now and then, although our brains do become good at filtering them out most of the time so that we can concentrate on what we really want to look at.

Sometimes there will be a condition, injury or infection that is causing the eye floaters. Underlying conditions that can cause floaters include short-sightedness and diabetes.

Serious symptoms

Changes in the frequency or size of your floaters could indicate that something more serious is going on. Here are some indicators that you should seek immediate medical attention from an eye specialist:

  • A sudden ‘shower’ of eye floaters
  • White flashes
  • Worsening vision

These symptoms could indicate a detached retina or another serious vision problem that requires attention.

Can they be treated?

Close up of blue eye: what causes eye floaters?For most people, eye floaters are at worst a minor distraction, so treatment is not needed. If yours are causing problems and you wish they would disappear, treatment options may be available to you:

  • A vitrectomy is a surgical operation to remove the vitreous humour from the centre of the eye, thus removing the cause of the floaters, and replacing it with a saline solution. This is an invasive procedure that carries risks including infection and retinal detachment. It is not usually recommended to patients because the risks tend to outweigh the likely benefits of surgery.
  • Laser vitreolysis is a new type of laser eye surgery that uses a laser to break up large floaters so that they are no longer big enough to interfere with your day-to-day life.

More information

If you would like some more information about what causes eye floaters or are worried about your own eye condition, it’s best to receive a check-up. There could be a number of different underlying causes, and a specialist will be able to give you the care and attention you need to diagnose the problem and treat it.