Flashes and Floaters

Below is information about the condition and how best to treat it. A PDF version is available at the bottom of the page.

What are they?

The eye is filled with a clear, jelly– like substance called the vitreous humour that helps maintain the eye’s shape. Debris within the vitreous humour casts a shadow on the retina at the back of the eye, and appears to ‘float’ in your field of vision. Floaters can appear in a variety of shapes and sizes such as black dots, smoke, shadow or hairs. They are more visible against clear, pale backgrounds such as white walls or blue sky. They move when your eye moves in different directions and seem to dart away when you look at them.

Most floaters are small but larger floaters can be annoying and make activities that require higher concentration, such as reading or driving more difficult. Although most people naturally experience floaters, and they are usually harmless, they can be caused by a Posterior Vitreous Detachment (PVD) or a detachment or tear of the retina (the light sensitive tissue inside the eye), which are serious conditions These can also cause symptoms of “flashing lights”.

What causes it?

Changes in the vitreous humour occur over a lifetime. With age, strands of collagen start to become visible within the vitreous humour and it is the shadow of these strands that gives the sensation of floaters. Light travels through the clear layer of vitreous humour in order to reach the retina, which then transmits images to your brain via the optic nerve.

When you are young, the vitreous humour is attached to the retina, but it starts to shrink and change over time and can pull away from the retina – this is known as a PVD. A PVD can cause floaters and also “flashing lights” by pulling on and stimulating the retina. This causes your brain to interpret the pulling as a light signal which creates the sensation of “flashes”.

If the retina tears or detaches, blood can escape into the vitreous humour, causing a “shower” of floaters and flashes. Retinal tears or detachments may also be the result of causes such as impact to the head or eye.

If you have floaters associated with flashing lights and/or distortion you should seek immediate medical/optical advice.

Who is at risk?

Everyone can be at risk of floaters, especially if you are myopic (short sighted) or play certain contact sports.

Floaters often occur in people over the age of 40 as the eye gets older; but are most common in people in their 60s and 70s.

Around half the population have a PVD by the time they are 50 years old, with most being unaware as they have not had any symptoms of flashes or floaters.

If you suddenly notice a shower of new floaters, or floaters along with flashes or a dark shadow or “curtain in your vision, these symptoms can mean the retina is tearing. To investigate this you should visit your Optometrist or Ophthalmologist (eye hospital specialist) immediately.

What are the symptoms?

Many people do not notice floaters as the brain constantly adapts to changes in vision. However a sudden onset of floaters or flashing lights can indicate something more serious. The symptoms are never painful.

Consult your Optometrist immediately if you:

  • Notice a sudden increase in the number of the floaters, or they start to look different
  • Start to see flashing lights
  • Have experienced floaters in one eye but they now appear more noticeable or appear in the other eye
  • Have floaters which make it difficult to carry out everyday tasks, such as driving or reading
  • Have a grey area, shadows, or hair-like areas appearing in your vision

How is it treated?

Floaters do not usually cause long-term visual impairment; but you should tell your Optometrist if they occur.

The Optometrist will check your vision and examine the back of your eye using a microscope. Drops will enlarge the pupil giving the Optometrist a better view of the inside of the eye; and your peripheral vision may be checked using a visual fields analyser. If it is suspected that you have a retinal tear or detachment you will be referred to a hospital.

Eye drops will not make floaters disappear. If one appears in your line of vision, try moving your eye quickly up then down. This causes the vitreous humour to swirl about and move the floater else where.

If you have any queries please feel free to contact us.