Eye Health

Flashes and Floaters


You may see flashes of light in front of one of your eyes, like small sparkles, lightening or fireworks. These tend to be in the extreme corners of your vision, come and go, and don’t obscure any part of your vision. The flashes don’t last for a defined length of time, and you may notice them more if you go from a light to a dark environment.

Flashes can occur when the gel in your eye becomes more liquid and “tugs” on the retina or may occur if you receive a blow to the eye or the head. However, constant flashes may indicate a retinal tear or detachment and may be accompanied by a shadow at the edge of your vision. If this happens you should contact us straight away.

Flashes and migraines

You may experience shimmering or zig-zag patterns if you suffer with migraines. Migraine shimmers are a flickering of light, often only on one side of your vision, in both eyes and have a sort of jagged pattern. They often obscure at least part of your vision (central, left or right). The shimmers can move across your visual field and usually go away after 10-20 minutes. They may be followed by a headache, although some people may get migraine shimmers even if they do not have a headache afterwards – we call this an ocular migraine.


Floaters appear as black spots or something that looks like a spider or a hair across your vision. These can be semi-transparent or dark and appear to float. Because they ‘float’ in the jelly of your eye, if you try to look directly at your floaters they shoot off and it’s hard to ‘catch up’ with them. The numbers of these floaters can increase as you get older. Occasionally an increase in floaters can be a sign of problems inside the eye, so if you notice a lot more floaters than you usually have you should contact us immediately.

You’re more likely to be aware of your floaters if you’re staring at a light coloured surface or at the bright sky. Some people find that floaters can be a nuisance, but most people become used to them. If you’ve had these for years your eye and your brain can learn to ignore them. They rarely cause serious problems.

Why do floaters occur?

Some people are born with floaters. Other floaters occur as you get older when the gel in the eye, the vitreous humour, naturally shrinks. Floaters can also be caused by some eye diseases that cause inflammation. This is not very common.

Who is at Risk?

You are more at risk if you:

  • Are significantly short-sighted
  • Have had an eye operation such as cataract surgery
  • Have had laser treatment after cataract surgery

What should I do if I have floaters?

Most of the time floaters are harmless. Sometimes they may be annoying, but treatment is not necessary.

Occasionally a sudden increase in floaters – either one or more large ones or a shower of tiny ones – along with flashes may be a sign of a more serious eye disease such as retinal detachment. If you experience this it is vital that you see our optometrist immediately – you should Request an appointment to see us that same day or go straight to A&E if our practice is closed.