Floaters are opacities in the vitreous jelly of the eye...
They cast a shadow on the retina and generally take the form of small dots, irregular rings and general cloudiness. To find out more about their causes and treatments, read on…
Floaters are opacities in the vitreous jelly of the eye. They cast a shadow on the retina and generally take the form of small dots, irregular rings and general cloudiness. The quality of the visual disturbance depends both on the mobility of the jelly and the position of the opacity – an opacity close to the retina tends to cast a more precise shadow, whereas opacity behind the lens of the eye is perceived as more of a mistiness. As not all opacities will cast a precise shadow the term “floater” can be misleading and a better term for this condition is Symptomatic Vitreous Opacity or SVO.
The key to diagnosing floaters is that they move independently of the eye, continuing to drift even when the eye is still.
It is helpful to know a little about the eye and how it works in order to understand the effect floaters have on your vision, and how they can be treated. Visit our Learning section to find out more about the biology of the eye.
The vitreous is the clear jelly-like substance which fills the hollow space behind the lens. As we age, the vitreous gel opacifies and eventually may shrink away from the retina. This is very common, occurring in about 75% of people over the age of 65.
Although floaters can occur when the gel is still attached, they are much more common when separation of the vitreous gel from the retina occurs. This is known as posterior vitreous detachment or “PVD”. It does not itself cause any permanent loss of vision, although very occasionally PVD results in tearing of the retina, with the risk of retinal detachment.
The appearance of floaters is also more common following cataract surgery.
In childhood the vitreous jelly is anchored to the retina and is essentially a clear structure. The composition of vitreous is more than 98% salty water (aqueous), with collagen making up much of the remaining 2%. As we age, the regular structure of the collagen network is lost and vitreous breaks down, with solid components separating from the salty water. A thicker “carpet” of jelly, known as the vitreous cortex, remains attached to the retina for many years, but in most people this eventually separates. It is normal for a few floaters to appear over the years, but at some stage a sudden shrinkage or collapse of the jelly results in posterior vitreous detachment. We can think of this as the carpet of jelly separating from the retina and falling into the salty water. This is an acute event, usually perceived as a sudden shower of floaters or awareness of a marked increase in symptomatic vitreous opacity.
Common symptoms of floaters are:
- small spots or “cobwebs” which flick across the field of vision on eye movement
- a generalised mistiness of vision, often described as “frogspawn”
- glare and increased difficulty in bright light.
Symptomatic vitreous opacity does not in itself cause damage to the eye, so the need for surgery is based entirely on your symptoms and the impact they have on your daily activities. We will help you decide if an operation to remove your floaters is appropriate for you.