POSTERIOR VITREOUS DETACHMENT
A Posterior Vitreous Detachment (PVD) is a very common cause of abrupt, new-onset eye floaters usually experienced by those over 50 years of age. In the general population, without asking about any symptoms, we would find 25% of 60 year olds, and 60% of 80 year old people will have evidence of a PVD.
Not all PVDs are symptomatic, and it is possible to have really bothersome floaters without a PVD. The PVD 'event' is a peeling away, a separation of the outer membrane (surrounding the vitreous) away from the retina - NOT to be confused with a retinal detachment. A retinal detachment is much much less common but it is an eye emergency and needs to be evaluated and treated promptly.
The membrane can peel away abruptly, or over the course of days or weeks, or rarely it may take years before it completely separates. How would you know? Well, a 2-D ultrasound may image it, but also, if the membrane is still attached to some of the underlying retina, the movement and shift of the fluid as occurs simply with head or eye movement may cause some traction on the retina. The only thing the retina can do with that 'stimulus' is to perceive it as a 'flash' of light, usually seen out in the periphery.
Unfortunately, a retinal detachment can also create the flashes of light. So good advice is that any new-onset peripheral flashes of light should be evaluated by a local, qualified eye care professional. A non-dilated photograph (common in optometry offices) is not adequate (in my opinion).
A PVD can not be 'repaired' in the sense that it can not be reattached. The good news, though, is that it can only happen once in an eye. After a PVD has completed, the floater situation is probably pretty stable and shouldn't get much worse. So if the eye floaters are minor and not too bothersome, nothing really needs to be done.
As far as treatment goes, in that older patient demographic, a PVD event is responsible for a lot of new patient treatments. Compared to the younger patients in their 20's-30's I can almost always treat the bothersome floaters with a laser after a PVD.
These videos will be helpful in explaining more details.