Floaters and Flashing Lights

‘Floaters’ are extremely common, and are sometimes associated with flashing lights in the eye, especially when they first appear. When they first appear, they normally affect one eye, but may occasionally affect both eyes at the same time.

In fact, they’re so common, that approximately two thirds of the population will have ‘floaters’ by the time they are in their mid-sixties! However, they can occur at any age.

What do Floaters look like?

Most people describe floaters as little ‘blobs’ or ‘cobwebs’ or ‘string like’ or ‘amoeba like’ features that move around in the eye, and can be best seen when looking at a light plain surface. However, floaters can take any number of appearances and are different in everybody.

What causes these floaters?

The commonest cause of floaters is called ‘vitreous detachment’. The main section of the eyeball is filled with a special gel known as ‘the vitreous’. Normally, the gel is enclosed within a fine membrane sac that fills the back of the eye, and so the outer part of the membrane is in contact with the retina (which lines the inside of the eye).

As we mature, the fine membrane ruptures, allowing some of the fluid to move in between the membrane and the retina, causing the vitreous and membrane to peel away from the retina. The retina, which is like the film of a camera, is then able to see the outer part of this gel and membrane (debris) floating inside the eye – and shadows caused by the debris is what causes floaters.

Sometimes, when the vitreous gel comes away from the retina, it can cause a hole or tear to appear in the retina. This is because the vitreous gel is sometimes more strongly attached to the retina in places. As the gel falls away from the retina (A bit like wall-paper falling from the wall), the gel can tear the retina (Like the wallpaper may take a piece of paint or plaster from the wall).

What causes the Flashing Lights?

The retinal nerve fibres are sensitive to heat and mechanical action, as well as to light.  As the gel comes away from the retina, firmly adherent gel may result in a tractional pull on the retinal tissue and could cause the appearance of flashing lights in the eye. Once the traction has ceased, the flashing lights normally subside as the gel releases its retinal hold. Occasionally, this tug-of-war between the gel and the retina results in the retina being pulled away and causing a retinal break or tear.

Why do I need my eye examined if I have new onset Floaters and/or Flashing Lights?

A strongly adherent vitreous detachment may tear the retina. If a hole or tear develops in the retina, then there is an increased risk of there being a full retinal detachment. A detached retina causes loss of vision, and requires a surgical ointervention to put the retina back in the right place. Thus, it is very important that you have your eye examined urgently on the onset of symptoms. There are other less common reasons for floaters – e.g. bleeding into the gel in the back of the eye from a blood vessel (usually in diabetic patients).

Should I be worried about Floaters?

Most floaters are harmless and there is no need to worry. However, if you have had new onset of floaters, or an increase in number or pattern, then you need to have your eyes examined by an optometrist as a matter of urgency. THIS IS ESPECIALLY IMPORTANT IF YOU ARE SHORT SIGHTED.

By seeing an optometrist early, if there is a problem, it can be diagnosed and treated before it progresses into something more serious.