Floaters

Page last reviewed: 13/07/2011

Floaters are the small shapes that some people see floating in their field of vision. They can be different shapes and sizes, and they appear to be floating in front of everything that a person is looking at. They may appear as:

  • tiny black dots  
  • small, shadowy dots  
  • larger cloud-like spots 
  • long, narrow strands

For more information, see Floaters - symptoms.

Floaters occur in the vitreous jelly of the eye, which is usually clear. They are pieces of debris that cast shadows onto the retina. It is the shadows that someone who has floaters is able to see.

Floaters most commonly develop as part of the natural ageing process, as the eyes get older. In most cases, they do not cause any significant problems and do not require treatment.

Do floaters affect vision?

Sometimes, a person may have floaters without noticing them. This is because the brain constantly adapts to changes in vision and learns to ignore floaters so that they do not affect vision. Most people with floaters will notice them at some point, although they do not permanently affect a person's vision.

Most floaters are not a sign of another eye problem. However, developing floaters or having floaters that get worse can be signs of other eye conditions that may affect sight, such as retinal detachment (when the retina becomes separated from the inner wall of the eye). See Floaters - causes for more information.

You should have your eyes examined immediately if you suddenly develop floaters or if you notice an increase in floaters. See Floaters - diagnosis for more information.

Page last reviewed: 13/07/2011

If you have floaters, you may not notice them all the time. When your eyes are still, or you are gazing into space, you may see them drift slowly across your vision.

Floaters are usually grey and semi-transparent. They may move when you move your eyes. When you move your eyes to look in different directions, the floaters may appear to move quickly. However, floaters do not tend to follow your eye movement precisely and they will often seem to dart away as you try to look directly at them.

Different forms of floaters

Floaters can occur in a variety of different forms. They may appear as:

  • dots 
  • circles 
  • lines 
  • cobwebs 
  • other shapes

You may notice lots of small floaters in your field of vision or just one or two larger ones. Most floaters are small and quickly move out of your field of vision. Larger floaters can be distracting and make activities that involve high levels of concentration, such as reading or driving, difficult.

Floaters are often most noticeable when you are looking at a clear-coloured background, such as a white wall or a clear sky.

 
Retina
The light-sensitive tissue that lines the back of the eye.

Retinal detachment

In rare cases, floaters may be a sign of retinal detachment (when the retina separates from the wall at the back of the eye). If you have retinal detachment, you will usually have:

  • a large number of floaters
  • bright, flashing lights
  • some loss of vision

If you think that you may have retinal detachment, seek urgent medical attention from your GP or optometrist (optician).

See Floaters - causes for more information about retinal tears and retinal detachment.

Page last reviewed: 13/07/2011

Floaters are small pieces of debris that float in the vitreous humour of the eye. They occur behind the lens (a small clear structure that focuses the light entering your eye) and in front of the retina (the light-sensitive tissue that lines the back of the eye).

Vitreous humour is a clear, jelly-like substance that fills the space in the middle of the eyeball. It is mostly made up of water (99%). The other 1% is made up of substances that help to maintain the shape of the vitreous.

Floaters occur as part of the natural ageing process. Some people may have posterior vitreous detachment (PVD), which may cause a sudden increase in the number of floaters they have.

Getting older

As you get older, your risk of developing floaters increases. Floaters tend to occur in people who are over 40 years of age and are most common in those who are in their 60s and 70s. However, some younger people may also develop floaters.

As you get older, the vitreous humour in the middle of your eyeball can become less firm and strands of a protein called collagen may become visible within it. The collagen strands may appear to swirl as your eyes move.

Normally, light travels through the clear layer of vitreous humour to reach the retina. The retina is the light-sensitive layer of cells and tissue at the back of your eye that transmits images to your brain via the optic nerve. Any objects that are in the vitreous humour, such as floaters, will cast shadows onto the retina.

Posterior vitreous detachment (PVD)

Floaters can be a symptom of posterior vitreous detachment (PVD). This is a common condition that occurs in about three-quarters of people over 65 years of age. PVD can occur as the result of changes to the vitreous humour as the eye gets older.

With age, the central part of the vitreous humour becomes more liquid and the outer part, known as the cortex (which contains more collagen), starts to shrink away from the retina. Floaters develop as a result of the collagen thickening and clumping together.

As well as floaters, flashing lights can be another symptom of PVD. Flashing lights may occur when the outer part of the vitreous humour pulls on the light-sensitive tissue of the retina. The pulling stimulates the retina, causing your brain to interpret it as a light signal. This creates the sensation of flashing lights.

Retinal tears

In approximately half of all people, the vitreous humour has separated from the retina by the time they are 50 years of age. This does not usually cause any problems and most people are not even aware that it has happened.

In a few cases of PVD, when the vitreous humour pulls on the retina it can cause the tiny blood vessels in the retina to burst and bleed into the vitreous humour. The red blood cells may appear as tiny black dots or they may look like smoke. However, as the blood is absorbed back into the retina, these floaters tend to disappear over the course of a few months.

In some cases, the vitreous humour remains attached to parts of the retina and it tears the retina as it pulls away. If the retina tears, blood that escapes into the vitreous humour can cause a shower of lots of floaters at once. You may also see flashes of bright, white light in your vision that look a little like lightning streaks.

It is important to be aware that flashes in your vision are not necessarily a sign of retinal tears or retinal detachment (see below). They may have another cause, such as a migraine with aura (a headache with a zigzag pattern across your field of vision).

Floaters and flashes do not usually cause long-term visual impairment, but if you experience them it is important that you visit an eye care specialist, such as an optometrist, to have an eye examination.

Retinal detachment

If you have a retinal tear, you will need to be treated as soon as possible because tears can lead to retinal detachment. Retinal detachment occurs when the retina separates from the wall at the back of the eye. If this happens, it can damage your sight.

After the light has passed through the eye and reaches the retina, the retina changes the light into meaningful electrical signals. The signals are sent through the optic nerve to the brain, where they are translated into the images that you see.

If the retina is damaged, the images that are received by your brain will become patchy or may be lost completely.

Retinal detachment is rare, affecting one person in every 10,000 every year. See the Health A-Z topic about Retinal detachment for more information about the condition.

Other causes

If you have had eye surgery, such as a cataract operation, you are more likely to experience floaters, PVD and, more rarely, retinal tears and retinal detachment. In some cases, floaters may also be caused by: 

Floaters are also more common in people who:

  • have short-sightedness (myopia), which causes distant objects to appear blurred, while close objects can still be seen clearly
  • have diabetes, which is a long-term condition that is caused by too much glucose (sugar) in the blood

As floaters and flashes can be caused by a number of eye conditions, some of which can affect your sight, it is always best to have any that develop checked by an eye care specialist. You should also visit a specialist if you have floaters or flashes that get worse.

See Floaters - diagnosis for more information about seeing an eye care specialist. 

Collagen
Collagen is a type of protein that is found throughout your body - for example, in your skin and in ligaments.
Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Optometrist
An optometrist (ophthalmic optician) examines eyes and tests sight. They can prescribe glasses and contact lenses, and are trained to recognise sight defects and eye diseases.
Retina
The light-sensitive tissue that lines the back of the eye.

Page last reviewed: 13/07/2011

Visiting your optometrist

Even though floaters are usually harmless and do not affect your vision, it is important that you visit an optometrist (optician) on a regular basis (at least once every two years). You should tell your optometrist if you have the symptoms of floaters.

Your optometrist will ask you about your:

  • symptoms, for example, how long you have had floaters
  • medical history, for example, whether you have previously injured your eye or had eye surgery

You should visit your optometrist immediately if a new floater appears suddenly or if there is a rapid increase in the number of floaters that you can see. They may refer you to an ophthalmologist (a specialist in treating eye conditions).

Floaters may be a sign of retinal tears or retinal detachment, although this is rare. The ophthalmologist will be able to check for this by examining your retina.

Eye examination

By looking through your pupil, the ophthalmologist will be able to see a small part of your retina. The pupil is the hole at the front of your eye that increases and decreases in size depending on light conditions.

If your ophthalmologist needs to get a clearer view of your retina, you may have a procedure known as dilation. This is where eye drops are used to make your pupil wider, allowing the whole of your retina to be examined.

The ophthalmologist may use an instrument called a slip lamp to examine your eyes. A slip lamp uses a lens and a bright light to enable the ophthalmologist to examine the inside of your eye. After the examination, your vision may be a little blurry and you may be sensitive to light for a few hours. 

Other tests

To get a better understanding of your eye symptoms, the ophthalmologist may also carry out a number of other tests. For example, they may:

  • ask you to look in different directions
  • push on your eye using a special instrument
  • examine your retina more closely using a very bright light

Eye pressure test (tonometry)

An eye pressure test (tonometry) uses an instrument called a tonometer to measure the pressure inside your eye (intraocular pressure). A small amount of anaesthetic (painkilling medication) and dye is placed onto your cornea (the transparent layer of tissue that covers the front of the eye).

A blue light from the head of the tonometer is held against your eye to measure the intraocular pressure. If the intraocular pressure is reduced it may be a sign of retinal detachment.

Ophthalmologist
An ophthalmologist is a medical doctor who specialises in eye disease and its treatment or surgery. They mainly work in hospitals and hospital eye departments.
Optometrist
An optometrist (ophthalmic optician) examines eyes and tests sight. They can prescribe glasses and contact lenses, and are trained to recognise sight defects and eye diseases.
Retina
The light-sensitive tissue that lines the back of the eye.

Page last reviewed: 13/07/2011

In most cases, floaters do not cause any significant problems and do not require treatment. Eye drops or other similar forms of medication are ineffective and will not make floaters disappear.

After a while, your brain may learn to ignore floaters and you may not notice them. If a floater appears directly in your line of vision, moving your eye up and down may help. It will cause the vitreous humour in your eye to move around, which may help by shifting the floater elsewhere.

Monitoring your condition

Your optometrist (optician) may ask you to return for a follow-up appointment two to six months after your symptoms began to check that your retina is stable. The retina is the light-sensitive layer of cells and tissue at the back of your eye.

If your vision is fine and your floaters are not getting worse, you may be advised to have appointments every one or two years. If your symptoms worsen at any time, you should seek immediate medical advice, either from your optometrist or GP.

Vitrectomy

A vitrectomy is a surgical procedure to remove the vitreous humour in your eye along with any floating debris and replace it with a saline (salty) solution.

A vitrectomy may be a possible treatment if your floaters do not improve over time, or if they significantly affect your vision. However, vitrectomies are rarely carried out due to the associated risks of eye surgery.

Before having a vitrectomy your eye will be numbed with a local anaesthetic (painkilling medication). During the procedure, the vitreous humour will be removed from the vitreous body of your eye and replaced with saline solution.

As the vitreous humour is mostly made of water, you will not notice any difference after having a vitrectomy. However, possible complications of a vitrectomy may include:

Vitreous humour
The clear, jelly-like substance that fills the space in the middle of the eyeball.

Page last reviewed: 13/07/2011

It is not possible to prevent floaters occurring because they are part of the natural ageing process. However, it is important that you are aware of the signs of retinal detachment so that you can seek an early diagnosis and treatment to protect your sight.

See your optometrist (optician) if:

  • you suddenly start to see floaters and white flashes having never seen them before 
  • you notice a sudden increase in the number of floaters or flashes 
  • you notice a grey area that appears in your outer vision and moves up, down or across your eye
  • you have had floaters or flashes for a while but they are now starting to look different 
  • you are finding it difficult to carry out day-to-day tasks, such as reading and driving 
  • you have had floaters or flashes in one eye for some time and they are now starting to affect your other eye
Retina
The light-sensitive tissue that lines the back of the eye.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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