Patient information · Eyes and urgent care
Flashes and floaters
usually harmless — occasionally sight-threatening
Floaters are extremely common and usually nothing more than the jelly inside the eye becoming more liquid with age. But a sudden change in floaters or flashes can mean the retina is tearing — and a tear caught early is treated in minutes, while a detachment left late may cost permanent sight.
Seek emergency eye assessment the same day if you have
- a sudden shower of new floaters, particularly many at once
- flashes of light, especially in the peripheral vision or in the dark
- a dark curtain, shadow or veil spreading across your vision
- a sudden loss of part of your field of vision
- sudden blurring of central vision, or straight lines appearing bent
- these symptoms after an eye injury or head injury
A retinal tear treated with laser before the retina detaches is a straightforward outpatient procedure. Once the retina detaches, surgery is required and the visual result depends heavily on whether the central vision was involved and for how long. This is measured in hours and days, not weeks. Moorfields Eye Hospital runs a 24-hour walk-in emergency eye service; the nearest emergency department is the Royal London Hospital, Whitechapel Road, London E1 1FR.
The common, harmless kind
Small specks, threads or cobwebs drifting across your vision, most noticeable against a bright plain background such as the sky or a white wall, moving as your eye moves and drifting on when it stops. These are shadows cast by strands in the vitreous jelly. They are extremely common from middle age onwards, tend to become less noticeable over months as the brain filters them out, and need no treatment.
What changes the picture
- Sudden onset rather than gradual
- Many new floaters at once, sometimes described as soot, smoke or a swarm of flies
- Flashes — brief arcs or streaks of light, typically at the edge of vision and worse in the dark
- Any loss of visual field, however small, or a shadow that is not moving with your eye
Posterior vitreous detachment
The commonest cause of sudden new floaters and flashes is the jelly peeling away from the retina — a normal ageing change affecting most people eventually. It is usually harmless. However, in a small proportion the jelly tears the retina as it separates, and there is no way to tell the difference without a dilated examination of the retina. That is why sudden new floaters and flashes always warrant an examination, even though most turn out to be fine.
Who is at higher risk
- Short-sightedness, particularly strong prescriptions — the commonest risk factor
- age over 50
- previous cataract surgery or other eye surgery
- a previous retinal tear or detachment, in either eye
- a family history of retinal detachment
- eye injury, and some inherited eye conditions
What examination involves
Drops are used to dilate the pupil, and the retina is examined in detail. Vision is blurred and light-sensitive for several hours afterwards, so you should not drive and should bring sunglasses. If a tear is found, laser or freezing treatment seals it, usually the same day and usually preventing detachment altogether.
Do not sit on new flashes or floaters. If your vision is affected or a shadow is spreading, go straight to an emergency eye service — that is faster than any appointment. But if you have new floaters without visual loss and want to be seen properly rather than wait, we can assess you the same day, seven days a week, examine the eye, exclude the causes that need urgent referral, and arrange same-day ophthalmology where the retina needs a dilated examination. No referral is needed and we are open 9am–7pm.
Seen today, referred fast if needed
Seven days a week, 9am–7pm. Visual loss needs emergency eye care now.
Tower Bridge Hospital London
97–99 Whitechapel Road, London E1 1DT
WhatsApp 07903 284 189
info@mhwclinic.co.uk
Open Mon–Sat, 9am–7pm (closed Sundays until September)
In an emergency
Call 999, or go to the Royal London Hospital Emergency Department, Whitechapel Road, London E1 1FR.
When we are closed and it is not an emergency
Call NHS 111 or visit 111.nhs.uk.