What are Flashes?

Flashes are sensations of light, when no light is really there. They may appear as many tiny bright lights (like ‘sparklers’) or like flashes of lightening. 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.

They may be more obvious with eye movement, or in a dark room. Some people with migraine headaches may experience a different type of flash.

These are usually shimmering, jagged lights that are present constantly for a period of fifteen minutes or so. They typically appear in the centre of your field of vision, and progress slowly towards the edges of the visual field.

A headache that is commonly throbbing, and on one side of the head, may follow the disappearance of the flashes.

What are Floaters?

Floaters appear as grey or black specs, lines, or ‘cobwebs’ in front of the eyes. As the eyes move, the floaters move too. They do not follow your eye movements precisely, as they usually drift when the eyes start or stop moving. Floaters are caused by clumps or bits of material suspended in the vitreous jelly that fills the back of the eye. The floaters cast shadows on the light sensitive retina. It is actually the shadow of the floater that you see. Floaters may have a variety of causes, some serious, and some not serious at all.

Should I be worried?

Many people have floaters. Floaters that you have had for years, and that show little change are usually not serious. It is the sudden onset of a new floater that may be serious. The onset of flashes may also be serious. Anyone with flashes or the sudden onset of a new floater (or floaters) should be examined promptly by an ophthalmologist/Optometrist. They will perform a dilated fundus exam (looking at the vitreous and retina with specialised equipment after giving drops to enlarge the pupils).

In most people, these drops have only a temporary effect on vision. You will not be able to drive afterwards. The effect of the drops will wear off within a few hours.

In extremely rare circumstances the drops can increase your eye pressure, so if you notice any of the following symptoms below.

  • Red painful eye
  • Haloes around lights
  • Nausea/Stomach cramps

You must go straight to your local eye casualty

Warning Signs

The most common cause of flashes is the vitreous humour (jelly) pulling away from the retina. This happens in over 70% of the population as part of the normal aging process, or for other reasons that are not well understood at this time. It is usually accompanied by floaters, which represent condensations of the vitreous jelly. By comparison, retinal breaks occur in approximately 6% of the population, and retinal detachments in about 0.06%. Light flashes occur in all three conditions.

What is the vitreous?

The vitreous is a jelly like material that fills most of the space inside the eye. As we age, the vitreous often liquefies and may collapse. This is more likely to occur, and occurs much earlier, in the eyes that are nearsighted (myopia). It can also occur after injuries to the eye or inflammation in the eye.

What is the retina?

The retina is a thin sheet of light sensitive nerve tissue that lines the inside of the eye. It is the tissue that turns light into an electrical signal to send to the brain. It can be compared to the film of a camera

What can be done about my floaters and flashes?

Your flashes are likely to go away on their own within a few days or a few weeks. This may be true even if you have a retinal tear or detachment! It is therefore important to be examined even if your flashes go away on their own. Floaters tend to last longer than flashes. In most cases, they diminish gradually over weeks or months. Often they do not go away completely. Most people learn to ignore them. Floaters, like flashes, may get better on their own even if a retinal tear or detachment is present. You should be examined even if the floaters seem to be going away.

Useful Telephone Numbers

Queens Medical Centre Eye Casualty
0115 924 99 24 ext 42882

Leicester Royal Infirmary Eye Casualty
0116 254 14 14