Eye floaters and flashes: when should you worry?
By See Better · Updated · 5 min read
The short answer
Most floaters are harmless specks or threads caused by normal age-related changes in the gel inside the eye. Get urgent help the same day if you suddenly see many new floaters, flashes of light, or a shadow or curtain over part of your vision. These can be signs of a retinal tear or detachment.
Key points
- A few long-standing floaters that have not changed are almost always harmless.
- A sudden shower of new floaters, new flashes or a shadow in your vision is an emergency.
- Short-sighted people and people over 50 are more likely to have floaters.
- Retinal tears are treatable if they are caught early.
What floaters are
Floaters are small shapes that drift across your vision. People describe them as dots, specks, threads, squiggly lines, cobwebs or little clear bubbles. They are easiest to see against something plain and bright, such as a blue sky, a white wall or a screen. When you try to look straight at one, it slides away.
They are not on the surface of your eye. The inside of the eye is filled with a clear jelly called the vitreous. As we get older, the jelly becomes more watery and forms tiny clumps and strands. These cast shadows on the retina at the back of the eye, and the shadows are what you see.
Why floaters appear
- Age. From about 50 the vitreous shrinks and eventually pulls away from the retina. This is called a posterior vitreous detachment. It is very common and usually harmless, and it often arrives with a noticeable new floater or two.
- Short-sightedness. Short-sighted people tend to get floaters earlier.
- After cataract surgery or an eye injury.
- Inflammation or bleeding inside the eye. These are less common, and diabetes is one cause of bleeding.
What flashes are
Flashes look like brief flickers, sparks or arcs of light at the edge of your vision, often most obvious in the dark. They happen when the shrinking vitreous tugs on the retina. The retina can only signal one thing, light, so pulling on it produces a flash.
Occasional flashes as the vitreous separates can be harmless. But the same tugging can sometimes tear the retina, which is why new flashes always need to be checked.
When floaters and flashes are an emergency
See an eye doctor or go to an emergency unit the same day if you notice a sudden shower of new floaters, new flashes of light, a dark shadow or curtain moving across part of your vision, or a sudden drop in vision. Do not wait to see whether it settles.
These are the warning signs of a retinal tear or a retinal detachment, where the retina peels away from the back of the eye. A tear can usually be sealed with a quick laser treatment. A detachment needs surgery, and the sooner it is done, the more sight is saved. It is painless, so the visual symptoms are the only warning you get.
You are at higher risk if you:
- are very short-sighted
- have had cataract or other eye surgery
- have had a retinal tear or detachment in the other eye, or have a close relative who has
- have had a blow to the eye or head
- have diabetic eye disease
When floaters are harmless
Floaters are very unlikely to be a problem if:
- you have had the same few for months or years
- they have not increased in number or size
- there are no flashes, no shadow and no change in your vision
The brain is good at tuning these out, and most people stop noticing them. Moving your eyes up and down can shift a floater out of your line of sight for a while.
Flashes that are not from the eye
A migraine aura can also cause visual disturbances, and it looks different. It typically appears as a shimmering, zigzag or jagged arc that slowly grows over 10 to 30 minutes, affects both eyes and may be followed by a headache. A first episode like this should still be discussed with a doctor, particularly if it comes with weakness, numbness or difficulty speaking.
How floaters are treated
Usually they are not treated. Harmless floaters need no treatment and tend to become less noticeable with time. No eye drops, exercises or supplements dissolve them. For the rare person whose floaters seriously interfere with vision, an ophthalmologist may discuss surgery or laser treatment, both of which carry their own risks.
The role of routine eye tests
A routine eye test checks the health of the back of your eye and is the time to mention any floaters you have noticed. If you are short-sighted or over 50, regular tests matter all the more. See how often you should have an eye test.
A home eye test is not the place for sudden symptoms, though. Those need urgent, specialised examination. Eye emergencies: when to get help explains where to go.
Frequently asked questions
Are eye floaters normal?
Yes. Most people have a few, especially from middle age onwards, and they are usually a harmless result of changes in the gel inside the eye.
Do floaters go away?
They often settle lower in the eye and become less noticeable over weeks to months, and your brain learns to ignore them. They seldom disappear completely.
Can stress or tiredness cause floaters?
Stress does not create floaters, but when you are tired or anxious you may notice existing ones more. A sudden increase should never be put down to stress without an eye examination.
What does a retinal detachment look like?
Typically a sudden burst of new floaters and flashes, followed by a grey or dark shadow that spreads from the edge of your vision like a curtain. It is painless. It is an emergency that needs treatment the same day.
This article is general information and is not a diagnosis or a substitute for an eye examination. If you are worried about your eyes or your sight, see an optometrist or a doctor. Sudden loss of vision, eye injuries and severe eye pain are emergencies.
