POSTERIOR VITREOUS DETACHMENT
What is a Posterior Vitreous Detachment?
The vitreous body, a clear jelly-like substance supported by delicate collagen fibres, occupies the back chamber of your eye. The retina, the sensory part of the eye which collects visual images, lines the inside of the eye surrounding the vitreous body.
As part of the normal ageing, the vitreous body changes character. Pockets of fluid form within its jelly-like substance and at the same time the collagen fibrils clump together (A). These changes may be seen as black or grey shapes, wavy lines or dots, floating about in your vision referred to as floaters or cobwebs.
With time the pockets of fluid enlarge and coalesce. If this fluid breaks-through the back of the vitreous body it allows it to detach from the retina and fall forward (B). At it peels off the inside of the retina it pulls on the retina causing the sensation of flashing lights. This process is called a posterior vitreous detachment and may take several weeks / months to complete.
Posterior vitreous detachments are very common, as a rule-of-thumb 50% of 50 year olds , 60% of 60 year olds etc.. are affected. They are more common in people who are short sighted, have suffered eye trauma or internal eye inflammation.
A small percentage of sudden recent onset posterior vitreous detachments are complicated by the development of tears in the retina (C). These tears occur when the detaching vitreous body pulls hard enough upon the retina (usually around blood vessels or areas of retinal degeneration) to tear it. If a tear occurs, fluid can get underneath the retina allowing it to detach from the inside of the eye causing a retinal detachment - a serious ocular problem that requires an operation.
It is important to understand that most posterior vitreous detachments are uncomplicated, innocuous events. However, because of the association of retinal tears and retinal detachments, it is very important to have your eyes thoroughly examined, through dilated pupils, so that any tears can be detected and treated before a retinal detachment can occur.
What will happen to the flashes and floaters?
Over a period of several weeks / months the vitreous will separate from the retina and the flashing lights will subside - the danger period of developing a retinal tear and detachment being essentially over. However, you may be left with harmless floaters which in time will become less noticeable as the shadows they cast upon the retina become less distinct.
What are the symptoms of retinal detachment or retinal tear?
Increased flashing lights
A shower of new / tiny floaters – may indicate bleeding into the eye
A growing dark shadow in / at the edge of your vision - may waft back + forth as the eye moves
Loss of vision
Misty / murky vision
To check for visual defects:
Cover one eye at a time.
Look straight ahead of you.
While doing so, examine your peripheral vision for defects.
What to do if any of the above occur?
You should make immediate arrangements for urgent assessment by your optician, eye-doctor or the hospital eye emergency service.
Delay may result in a retinal detachment, which could leave you with permanent poor vision.
How is retinal damage treated?
Retinal tears are usually amenable to simple laser treatment the same day.
Left untreated, a sight threatening retinal detachment may occur that will require surgery. The visual outcome depending greatly upon the severity of the retinal detachment.