Most floaters are harmless and permanent. A sudden new one, a shower of spots, or flashes of light are a different matter and need checking the same day.
What floaters actually are
The inside of the eye is filled with vitreous, a clear gel that gives the eyeball its shape. With age that gel thins, shrinks and separates into watery pockets, and the fine collagen fibres suspended in it clump together into strands and specks.
Those clumps do not float across vision. They float across the light coming into the eye, and what gets noticed is their shadow falling on the retina behind them. That explains most of their behaviour: they drift when the eye moves and then overshoot and settle, they cannot be looked at directly because they move with the gaze, and they are far more obvious against a blank bright background — a white wall, a page, an overcast sky.
They look like threads, cobwebs, rings, dots or translucent worms. Almost everyone has some by middle age, and once present they are permanent, although the brain learns to ignore them remarkably well.
Flashes are not floaters
This is the distinction that matters, and the one most often blurred.
A floater is a shadow cast by something inside the eye. A flash is not a shadow at all — it is the retina itself being tugged. As the vitreous shrinks it pulls on the retina, and the retina interprets any mechanical stimulation as light, because light is the only thing it knows how to report. The result is an arc or streak of brightness, usually at the edge of vision, often brief, and more obvious in dim surroundings or when the eyes move suddenly.
Flashes therefore mean traction on the retina, and traction is the thing that can tear it. That is why flashes carry weight that floaters alone do not.
One common look-alike is worth knowing. Migraine can produce flashes too, but they look different: jagged zig-zag lines, shimmering or expanding, typically present in both eyes at once, and lasting somewhere between ten minutes and an hour. A headache may or may not follow. Retinal flashes are usually in one eye only and far briefer.
Posterior vitreous detachment
Most new floaters in later life arrive as part of a single event: the vitreous finally peeling away from the back of the eye. This is posterior vitreous detachment, it happens to most people eventually, and in itself it is harmless.
It usually announces itself with a sudden increase in floaters — frequently one large ring or cobweb, which is the edge of the detached membrane — often accompanied by flashes while the separation is in progress. The symptoms settle over weeks or months.
The reason it matters is that this is the moment when the retina is most likely to tear. The vitreous does not always let go cleanly; where it is firmly attached, the pull can take a piece of retina with it. A tear allows fluid behind the retina, and the retina lifts away from the wall of the eye. That is a retinal detachment, and it threatens sight permanently.
So the event itself is routine, and the small minority of cases that go wrong do so at a predictable moment. This is precisely why a sudden change in floaters is worth examining rather than waiting out.
When it is urgent
Any of the following needs an eye examination the same day:
- a new floater appearing suddenly — even one
- a sudden shower of spots, often described as soot, pepper or a swarm of flies
- flashes of light, particularly new ones or ones accompanied by floaters
- a dark shadow or curtain spreading across any part of the field of vision
- loss of side vision
- a sudden drop in the clarity of central vision
The last three suggest the retina may already be detaching, and warrant going straight to an emergency department rather than booking anything.
For the first three, a same-day appointment with an optometrist or a GP is the right step; most optometrists will fit in an urgent case and have the equipment to examine the retina properly through dilated pupils. NHS 111 can direct to an urgent eye service where one exists locally.
The instruction that applies to everyone, including people who have had floaters for decades: new ones get looked at straight away. Long-standing floaters are reassuring about themselves and say nothing about the one that appeared this morning.
Waiting is the specific thing to avoid. A tear that is found early can be sealed with laser in an outpatient appointment, and the eye usually keeps its sight. A detachment that has spread needs surgery and may not recover fully. The gap between those two outcomes is frequently a matter of days.
Who sees more of them
Floaters become more common with age, and particularly from the forties onwards as the vitreous begins to change.
Several groups experience both floaters and posterior vitreous detachment earlier or more often: people who are short-sighted, in whom the eye is longer and the vitreous under more strain; anyone who has had cataract surgery or YAG laser treatment afterwards; and anyone who has had inflammation inside the eye. Injury to the eye and diabetic changes in the retina can also produce floaters, including ones caused by bleeding rather than by gel.
Belonging to any of these groups is not cause for alarm. It is a reason to treat a sudden change with slightly less scepticism than someone else might.
What can be done about ordinary floaters
The old answer — nothing at all — is not quite right in either direction.
Most floaters need no treatment, and the realistic good news is that they become less troublesome without going anywhere. Some settle below the line of sight, many break down over months, and the brain gradually stops reporting them. Looking up and down briefly can shift one out of the way when it parks itself somewhere inconvenient.
Where floaters genuinely interfere with vision, two procedures exist. Vitrectomy removes the vitreous surgically and replaces it with fluid; it is effective and carries real risks, including cataract and a small chance of retinal detachment, so retinal surgeons reserve it for severe cases after careful assessment. YAG laser vitreolysis, which aims to break up individual floaters, is not available on the NHS.
Neither is a casual option, and the balance of benefit against risk is the whole conversation. But the flat statement that nothing can be done is wrong — and it is especially wrong where the cause turns out to be a tear, in which case there is a treatment, it works, and it is urgent.
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