Flashes & Floaters

Floaters are caused by clumps or bits of material suspended in the vitreous jelly that fills the back of the eye. It’s actually the shadow the floater casts on your light-sensitive retina that you see, not the floater itself.

As your eyes move, floaters move too — though they don’t follow your eye movements precisely, and tend to drift when the eyes start or stop moving. They appear as grey or black specs, lines, or ‘cobwebs’ in your vision.

Floaters have a variety of causes, some serious and some not. They become more common as the vitreous naturally liquefies and collapses with age, which tends to happen earlier if you’re short-sighted.

Most floaters are harmless. But a sudden increase, a new large floater, or floaters appearing alongside flashes of light should always be examined promptly by an optometrist.

Flashes may occur when the vitreous jelly pulls on or tears the retina. These flashes usually last for only a second or so, but typically occur repeatedly, and may be more obvious with eye movement or in a dark room.

Floaters are very common and normally harmless. Some people also see flashes of light — sensations of light when none is really there, often described as tiny ‘sparklers’ or flashes of lightning. These happen when the vitreous jelly pulls on or tears the retina, and usually settle down on their own after a few days or weeks.

Occasionally, though, flashes or an increase in floaters can point to something more serious, even retinal detachment, which needs prompt treatment. Watch out for a sudden shower of floaters, a new large floater, or floaters combined with flashes — these should still be examined thoroughly, even if less serious than the warning sign below.

The most serious warning sign is a shadow or curtain spreading across one of your eyes. This needs urgent attention from your local Eye Casualty department.

The most serious warning sign is a shadow or curtain that spreads across one of your eyes. If this happens, seek medical attention from your local Eye Casualty department as soon as possible — for example, Nottingham QMC Eye Casualty or Leicester Royal Infirmary Eye Casualty.

Anyone with flashes, or the sudden onset of a new floater, should be examined promptly by an optometrist. We’ll perform a dilated fundus exam — looking at the vitreous and retina with specialised equipment after giving drops to enlarge the pupils.

Other symptoms worth having checked include a sudden shower of floaters, a new large floater, or floaters combined with flashes of light. These are less serious than a shadow or curtain effect, but should still be examined thoroughly to rule out anything more significant.

If we need to use drops to enlarge your pupils for a dilated fundus exam, these usually have a temporary effect on vision and you will not be able to drive afterwards. The effect of the drops wears off within a few hours.