Flahes & Floaters
Posterior Vitreous Detachment (PVD)
Symptoms
- Do you see black or grey floating patterns in your vision?
- Are they more visible in bright background?
- Do you see flashing lights in the dark?
What is Posterior Vitreous Detachment?
The eye is mostly filled with transparent jelly called vitreous or vitreous humour. It has the consistency of raw egg white but is crystal clear. This fills the space behind the lens and in front of the retina. The vitreous is normally firmly attached behind the lens of the eye and to the front edge of the retina but only very loosely adherent at the back of the eye.
Over the years the vitreous degenerates and tends to shrink. While it does so, it separates from the back of the eye. This can occurs over few hours or many months. It is then free to rotate when you move your eyes. This process is called Posterior Vitreous Detachment?
Why do floaters develop?
When the vitreous degenerates, it forms little opaque condensations within its clear substance. These condensations cast a shadow on the retina whenever there is a bright background. They then appear as floaters. These floaters can take any shape and size. Because the vitreous now can rotate and move within the eye, these floaters can be seen to move. This is often annoying. Over a period of months the floater becomes less obvious as it moves away from the retina making the shadow less distinct.
Why do flashing lights develop?
Once the vitreous becomes loose, eye movements cause the vitreous to tug where it is still adherent to the retina. This irritates the retina and is perceived as a flash of light. These flashes are often only seen in the dark. With time the vitreous continues to separate from the retina until one day, it will become totally free. The flashing lights will then cease.
What is the concern with Flashes & Floaters?
In some people with a weak retina the moving vitreous can exert enough force to tear the retina causing a “hole” or “break”. When the retina tears it can cause a haemorrhage as fine blood vessels are embedded in the retina. You may see more floaters as dark blobs or lots of dots. These symptoms must be taken seriously since such retinal holes or breaks can lead on to retinal detachments.
What is Retinal Detachment?
Retinal Detachment is a separation of the retina from the back of the eye. They most commonly occur due to a tear caused by the mechanical forces of a separation of the vitreous. Fluid behind the vitreous can pass through the tear and progressively strip off the retina so that it balloons forwards. This prevents the retina from functioning properly and hence affects vision.
What can be done about Retinal Detachments?
If the retinal breaks or holes are picked up early before the retina had a chance to detach, these can be sealed very easily with Laser or Cryotherapy. Once the retina has detached, then treatment can only be done by complex surgery.
Careful examination by a trained ophthalmologist will identify such areas. Laser treatment is a simple procedure to seal the edges of the torn retina.
ADVICE
If you experience new floaters or flashing lights see your GP or optician and obtain a referral to an ophthalmologist. It is best to be seen within a few days of the onset of symptoms. If your symptoms have been present without much change over six months there is no need to take any action because your retina has survived the stress of having a vitreous detachment without causing a retinal tear.