Posterior Vitreous Detachment (PVD)

The eye is filled with a clear, jelly-like substance called the vitreous.  Made up of 99% water and 1% other substances, such as collagen, that maintain the shape of the eye.  The vitreous is attached to the retina (the back of the eye which receives light and sends messages to the brain).

What is Posterior Vitreous Detachment (PVD)?


Some parts of the vitreous are more firmly attached than others.  As people age the vitreous changes.  The central part becomes more liquid and the outer layer (the cortex) starts to peel away from the retina. 

In a small number of cases, if the vitreous is more strongly attached to the retina, tears may occur, which can lead to retinal detachment but this is rare.

PVD is very common, effecting 75% of people over 65.

Symptoms:

Sufferers usually notice "floaters" or flashing lights in their vision when they first develop PVD. 

Floaters are shapes that drift across the vision.  These can be in various forms, from small dots or circles to lines or cobweb-like strands but also one large shape that obsures vision as it floats across the eye.  They are usually more of a problem in bright light.

The appearance of flashing lights can also occur when the vitreous detaches from the retina, pulling and stimulating the light sensitive membrane which sends messages to the brain.  The brain interprets this stimulation as flashes of bright, white light.  An increase of floaters normally occurs when this happens and could lead to a detached retina.

If there is a sudden increase in floaters, especially with flashes of bright light, it is urgent the sufferer seeks immediate medical advice from from an eye specialist.
Retinal detachment can cause a "shadow" to spread across the vision of the effected eye, impairing vision.

Treatment:

There is currently no safe treatment for PVD.  The symptoms usually calm down after a few months and the sufferer gets used to the floaters, as the brain adapts and ignores them.  Although PVD takes time getting used to, the condition itself is essentially harmless and more of an annoyance than a permenant threat to sight.

The only real threat to vision is the small chance of a retinal tear or retinal detachment.  Early treatment to a retinal tear or detachment increases the chance of recovery, so seeking medical advice is very important.  If  caught early enough simple laser or freezinf treatment can be performed under local anisthetic.  However an operation may need to be performed to repair or put the retina back in place.

The amount of vision resored by the operation depending on the scale of the detachment and for how long it has been detached.  The shadow caused by the detachment is completely restored in most cases.  If the area of the retina used for seeing fine detail has been damaged this may not fully recover.

If no operation is performed for a detached retina most people will lose useful sight so if PVA symptoms increase it is important to see a doctor.

Links:

For a more detailed and expert opinion amd advice visit:

RNIB page Posterior Vitrous Detachment
Moorfields hospital on floater
Illustrated guide from Good Hope hospital