Eye floaters, eye floater, eye floater information

Some of the questions and answers people often ask about eye problems. This page deals with eye floaters, frequently asked questions and information relating to floaters in the eyes.

What are eye floaters?

Floaters are shadows which are cast on the retina by solid particles moving around in the vitreous cavity. The retina is the light sensitive membrane in the eye and in many ways can be compared to the film in a camera. The vitreous cavity is the back four-fifths of the eye and contains the vitreous jelly. Because the vitreous jelly is semi solid and constantly moving, the particles move around giving the appearance of something floating within the eye. Nearly everyone is aware of floaters from time to time particularly when looking at a bright blue sky or on a misty day. Such floaters are usually ‘normal’ or ‘physiological’.

Should I be worried about the presence of eye floaters?

Anyone who has suddenly developed floaters should receive an urgent eye assessment, as should anyone who has developed floaters that interfere with their vision. This is because floaters can be either due to or associated with potentially serious eye conditions. For example a posterior vitreous detachment may cause a retinal tear with the risk of a retinal detachment.
A hemorrhage in the eye could result from a retinal tear, complications of diabetes or other serious eye condition and require treatment. Individuals who develop inflammatory floaters have usually got a significant underlying eye disease which needs to be identified and treated. These conditions are explained in more detail below. In the majority of cases it is likely that no other sight threatening condition will be found.

What is a PVD?

By far the commonest cause of floaters is a Posterior Vitreous Detachment or PVD. This typically causes the sudden onset of floaters and occasional flashing lights. A PVD is rare before the age of 40 and may be present in about 2 out of 3 seventy year olds. The vitreous jelly normally fills the back four-fifths of the eye. With ageing, inflammation, surgery and short sightedness there is a tendency for the vitreous jelly to separate from the surface of the retina.
The posterior vitreous is usually glued to the surface of the retina at least at one point which is over the surface of the optic nerve head. When the vitreous detaches from the optic nerve head there is some naturally occurring glue left on the surface of the vitreous which is typically circular, oval or cobwebbed in shape. The glue is opaque and moves around causing a floating shadow. This is probably the commonest cause of floaters and is known as a Weis ring.

What other other causes of floaters are there?

There are many other causes of floaters including vitreous syneresis, bleeding into the eye and inflammation.

Physiological floaters.

Physiological floaters are floaters which are present in just about everyone to a greater or lesser extent. Most people are aware of the occasional dot or circle within their vision if they look at a bright light wall or a clear blue sky. Another time that people notice physiological floaters is in a misty or cloudy environment. Most people are aware that they have had these minor floaters for a long time and that they have not changed.

Vitreous syneresis.

The vitreous jelly is usually made up of a regular three dimensional meshwork of a combination of collagen protein, sugary compounds and salty water. Ordinarily this produces an optically clear colourless jelly which is 99% salty water and only 1% solid. With time this regular three dimensional latticework can break down.
This is followed by the formation of entirely fluid filled pockets within the vitreous jelly as shown in the picture above and clumps of the collagen fibres coalesce together to form strings or lumps which look a bit like teased out cotton wool.
The process of vitreous syneresis or breakdown is a natural phenomenon. It can, however, be exaggerated in people who have had eye surgery, shortsighted individuals, those who have had inflammation within the eye and as an unfortunate phenomenon in people with otherwise normal eyes. Syneretic floaters may be completely independent of the presence of a posterior vitreous detachment.