Floaters and flashes in the eye: what is normal and what is urgent

Noticing small specks, threads or cobwebs drifting across your vision can be unsettling, particularly the first time. Most floaters are harmless. A sudden change, though, can be a sign of a problem at the back of the eye that needs treatment quickly. This post explains what floaters and flashes are, which pattern is usually benign and which signs mean you should seek urgent eye care.

The short answer

• Floaters look like small specks, dots, circles, lines or cobwebs in your vision. They are tiny clumps of gel or cells in the vitreous, the jelly that fills the eye, casting shadows on the retina.
• The American Academy of Ophthalmology (AAO) says floaters are not usually serious and tend to fade and become less noticeable over time.
• Any new floaters or flashes should be examined by an eye professional.
• Get urgent help if you notice lots of new floaters, many flashes, a shadow in the side of your vision, or a grey curtain over part of your sight.

What floaters and flashes are

Floaters

The vitreous is clear and jelly-like. As we age, it can thicken or shrink, and clumps or strands form. You usually notice them when looking at something plain, such as a blank wall or a blue sky. The AAO says you are more likely to get floaters if you are short-sighted, have had cataract surgery, or have had inflammation inside the eye.

Sometimes the vitreous pulls away from the back of the eye, which is called posterior vitreous detachment (PVD). Floaters are more common with PVD, but you can have them without it.

Flashes

Flashes can look like flashing lights or lightning streaks, and some people compare them to seeing stars after a knock on the head. They happen when the vitreous rubs or pulls on the retina. The AAO says flashes may come and go for weeks or months, and seeing them occasionally is common with age.

Migraine light patterns

Light disturbances that look like jagged lines, shimmering spots or heat waves, appear in one or both eyes and last up to about an hour, may be caused by a migraine. They can happen with or without a headache. This pattern differs from a brief flash of light in one eye, but only an examination can tell them apart, so mention any new pattern to a professional.

When floaters and flashes are urgent

The NHS page on a detached retina says the retina is the thin layer at the back of the eye. When it becomes loose, it needs to be treated quickly to stop it permanently affecting sight. Symptoms include floaters or flashes of light, a dark curtain or shadow in the vision, and changes to eyesight such as blurred vision.

The AAO says to call an ophthalmologist right away if:

• you notice a lot of new floaters
• you have a lot of flashes
• a shadow appears in your side vision
• a grey curtain covers part of your vision

The NHS advises getting help urgently if floaters suddenly appear or suddenly increase in number, if you get flashes of light, if a dark curtain or shadow moves across your vision, or if your vision gets suddenly blurred.

If you cannot reach an eye professional quickly, go to an emergency department or call your local health helpline. Do not wait to see whether it settles.

Who is more likely to have a retinal detachment

The NHS says a detached retina is usually caused by changes to the jelly inside the eye with age, and that it is more likely if you are short-sighted or have had an eye operation such as cataract surgery. It is not clear why PVD leads to detachment in some people, and the NHS says there is nothing you can do to prevent it. This is why prompt assessment of new symptoms matters, rather than any lifestyle step.

What happens at an eye examination

For floaters or flashes, an eye professional will usually check your vision and look at the back of your eye, often using drops that widen the pupils. Ask beforehand whether the drops will affect your vision or your ability to drive afterwards, and consider bringing someone with you.

If the retina is torn or detached, the NHS says you will be referred to hospital for surgery. For harmless floaters, the usual outcome is reassurance and advice to return if things change. The AAO notes that severe floaters can be removed by surgery, but this has risks and is seldom necessary or recommended.

For general background on who does what, see our post on optometrists and ophthalmologists, and the eye test and glasses guide. The eye examination service page and the eye care topic have more.

Living with floaters

Many people get used to floaters, which are most noticeable against a plain bright background. If they affect daily life, tell your eye professional so that the options and risks can be discussed.

Frequently asked questions

Do floaters go away?

They often become less noticeable as the brain adjusts, and the AAO says they tend to fade over time. They do not always disappear completely.

Are floaters a sign of a stroke?

Typical floaters are an eye symptom. Sudden loss of vision, drooping of the face, weakness or difficulty speaking need emergency care at once.

Can screens cause floaters?

There is no evidence in the sources we reviewed that screens cause floaters. They relate to changes in the vitreous.

Should I have an eye test after seeing floaters?

Yes, particularly if they are new. The AAO says any new floaters or flashes should be examined by an ophthalmologist.

General information only

This article is general information, not medical advice. A sudden change in vision, a curtain across the sight, or eye pain after an injury needs urgent medical care. You can send an inquiry to ask HealthNaro for help finding an eye professional.