Floaters and flashes Whakarewanga

Dots and lines (floaters) or flashes of light in your vision are common, especially as you get older. They are not usually serious, particularly if you have had them for a long time, they are not getting worse, and your eyesight is not affected.

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When to get immediate medical attention

See your optometrist, ophthalmologist or healthcare provider immediately if you have any of these symptoms:

  • Flashes — suddenly seen during the daytime.
  • Floaters — new (in the past 1 or 2 weeks) or larger than before.
  • Falling curtain — a shadow or curtain appearing at the edges of your vision (peripheral vision) or a grey curtain moving across your vision.
  • Failing vision — rapid or sudden loss of vision.

You need to have these assessed urgently — on the same day. Over the weekend you can be assessed at an after-hours clinic. They can refer you to an ophthalmologist urgently if necessary.

Cause of floaters and flashes

The most common cause is posterior vitreous detachment. This is when the gel-like fluid in the back of your eye shrinks in size and pulls on the inner lining of your eye (retina).

Medical illustration of the eye showing the retina, floaters, detached vitreous, and vitreous fluid.

Floaters

Visual floaters are blobs, thread-like strands, fine cobwebs or just dull shadows and spots in your vision. They are more noticeable when you look at a white wall or plain, light-coloured surface such as the sky.

Floaters are actually particles within the clear gel-like substance that fills the inside of your eyeball (vitreous fluid). These particles cast shadows on your retina, the light-sensitive layer at the back of your eye. As you get older, floaters become more common.

The floaters move as your eye moves but tend to drift away when the movement stops.

Floaters are usually harmless, but annoying. They tend to become less noticeable with time.

If you suddenly get new floaters or a lot more floaters, you should get your eyes checked in case you have a retinal detachment.

Retinal detachment

Flashes

Flashes are sparks or strands of light that flicker across your vision.

If you see light flashes in dim light or at night, you do not usually need to worry.

If you see flashes of light during the daytime, you need to have your eyes checked urgently (on the same day) as this can be a sign of an early retinal detachment.

People with migraine can have a different type of light flash, called an aura. An aura is shimmery lights and zig-zag patterns in your vision, sometimes followed by 'blind areas'.

You may or may not get a headache or feel sick (nauseous) after an aura. If this is new for you, see your healthcare provider.