Flashes and floaters

Category: Head, Eyes, Ears, Nose & Throat · All head & senses symptoms

What it can feel like

Floaters are drifting specks, threads or cobwebs that move with the eye, caused by shadows from tiny clumps in the eye's gel. Flashes are brief flickers of light, usually at the edge of vision, caused by the gel tugging on the retina. Long-standing floaters are common and benign; a sudden shower of new floaters with flashes is a warning.

Possible causes

A symptom can have many causes, and most are not serious. The lists below group conditions this symptom can be associated with — common causes first. They are possibilities to discuss with a clinician, not a diagnosis.

Common causes

Floaters and flashes can be associated with normal ageing of the eye gel (posterior vitreous detachment), short sight (which stretches the eye), and migraine visual aura (usually in both eyes, with a pattern that marches and fades).

Other possible causes

A sudden increase in floaters, flashes, or a shadow or curtain spreading across vision can be associated with a retinal tear or detachment — an emergency in which prompt laser or surgery can save the sight of that eye.

Red flags — when to seek help promptly

A sudden shower of new floaters, or flashes, in one eye — same-day eye assessment
A shadow, veil or curtain spreading over any part of vision — emergency
Flashes and floaters after an eye injury
New floaters with a fall in vision in that eye

What a clinician may do

An eye specialist will dilate the pupil and examine the retina thoroughly, sometimes with a contact lens or ultrasound of the eye. A retinal tear can often be sealed with laser in clinic; a detachment needs surgery, and speed determines how much vision is preserved.

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Frequently asked questions

Why does a curtain over vision mean emergency?

The curtain is the detached retina losing function as it peels away. If the detachment reaches the centre (the macula), central vision is permanently damaged. Detachments caught while the macula is still attached have far better outcomes — hence same-day assessment for any shadow.

My floaters have been there for years — do I need checks?

Stable, long-standing floaters that were examined when they appeared generally need no further action. It is change — many new floaters, flashes joining them, or any shadow — that should trigger a fresh dilated examination.

Related symptoms — Head, Eyes, Ears, Nose & Throat

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Please note: This page is educational information about a symptom. A symptom alone cannot diagnose any condition, and the causes listed here are possibilities, not a diagnosis. If you are worried about a symptom — especially one that is new, severe, getting worse or not going away — please see your own clinician, who can examine you and arrange tests. In an emergency, call your local emergency number.