Floaters and flashes
Contact the clinic or attend an emergency eye department the same day if you have a sudden shower of new floaters, new flashing lights, or a shadow or curtain coming across your vision. Most cases turn out to be harmless, but a small number are a retinal tear or detachment, and those need treating quickly.
These are the questions that come up in clinic.
What are floaters?
Small shapes that drift across your vision — dots, threads, cobwebs, or a ring. They move when you move your eye and drift on when it stops.
They are shadows cast on the retina by clumps in the vitreous, the clear gel that fills the back of the eye. They are in the eye, not on it, which is why blinking and rubbing make no difference.
What are flashes?
Brief arcs or streaks of light, usually at the edge of your vision, often more noticeable in the dark.
They happen when the vitreous gel tugs on the retina. The retina interprets any stimulus as light, so a mechanical pull is seen as a flash.
Why have they appeared now?
Usually because of posterior vitreous detachment — the vitreous gel shrinking with age and peeling away from the retina.
It is a normal ageing change, commonest between the ages of 50 and 70, and earlier in people who are short-sighted. It is not a disease and it does not mean anything has gone wrong.
As it separates, it produces exactly these symptoms: a sudden increase in floaters, sometimes a large ring-shaped one, and flashes.
So why does it need checking?
Because in a small proportion of cases the gel pulls hard enough to tear the retina, and a tear can progress to a retinal detachment, which threatens sight.
A tear found early is treated with laser in a few minutes in clinic. A detachment needs surgery in theatre. The difference between those two outcomes is often just how quickly someone was seen.
That is the whole reason for the same-day advice.
What are the warning signs?
Seek assessment the same day if you have:
- a sudden shower of many new floaters, rather than one or two
- new flashing lights, particularly if they are frequent or persistent
- a dark shadow or curtain moving in from the edge of your vision
- a sudden drop in vision
- what looks like a puff of black smoke or soot in your vision
The last of those can mean bleeding into the vitreous, which is associated with a tear.
Longstanding, unchanged floaters that you have had for years are not urgent. It is a change that matters.
What happens at the appointment?
Your vision is checked, then dilating drops, which take about twenty minutes to work and blur your vision for a few hours. Arrange a lift — you should not drive afterwards.
The retina is then examined thoroughly, right out to the far periphery, which is where tears almost always occur. Scanning is available on site if it is needed.
The examination is the important part, and it cannot be rushed or done without dilating.
What if a tear is found?
It is usually sealed with laser retinopexy in clinic. The laser creates a ring of small scars around the tear, welding the retina down so fluid cannot get underneath and lift it.
It takes a few minutes, is done under anaesthetic drops, and you go home the same day.
What if the retina has detached?
That needs surgery, and it needs it promptly. You would be referred straight to a vitreoretinal surgeon.
The outcome depends heavily on whether the central macula is still attached, which is another reason not to wait and see.
Will the floaters go away?
They usually become much less noticeable over several months. The brain learns to filter them out, and they settle lower in the eye and out of the line of sight.
They rarely disappear entirely. Most people find that after six to twelve months they only notice them against a bright plain background — a white wall, the sky, a computer screen.
Is there any treatment for the floaters themselves?
For most people, no treatment is needed or advisable. Surgery to remove the vitreous carries real risks, and it is reserved for the small number whose floaters are genuinely disabling and stable.
If yours are severely affecting reading or work after they have settled, it is worth discussing rather than assuming nothing can be done.
Am I at higher risk?
Yes, if you are:
- short-sighted, particularly highly so
- post-cataract surgery
- post-injury to the eye
- someone who has already had a tear or detachment in either eye
- someone with a family history of retinal detachment
If any of those apply, take new symptoms seriously rather than waiting.
Next steps
Patients — if symptoms are new or changing, contact the clinic the same day.
GPs and optometrists — refer directly to Limerick or Ennis, including by Healthmail. Please mark urgent where there are new flashes, a shower of floaters, or any field defect.