Black eye floater - PVD?

I recently had a stringy black floater appear in my left eye, which i can see pretty much all the time, even on dark surfaces.  I went to an optometrist and an opthamologist who both said everything looked fine.  I

[Forum-OD-MP]

a PVD is usually very large and very noticable to the eye docs.  if you had *2* people dilate you and neither saw a PVD, then i'm going to say its pretty unlikely that you had one.  

just b/c you can see a floater doesnt mean we can.  what looks HUGE to you looks TINY to us looking in.  when you see your floater, you're looking at something that is less than a few mm from your retina.  we're loking at the same tiny thing, but upside down and backwards more than 2 feet away.  thats a big difference.

i see patients all the time who complain of floaters, but when i dilate them i dont see anything.  that doesnt mean it doesnt exists, that just means i cant see it...

[mits1]

Thanks for your response!
When you're examining patients, can you also see if the vitreous is 'shrinking' or 'liquifying' and if that would be a possible cause of the floaters that aren't visible.
Also, how do laser eye specialists go about 'breaking up' the floaters if they can't see them?

[Ag-i-doc]

yes, vitreal degeneration is sometimes obvious on examination.  but sometimes its not.

nobody can laser and break up a floater that they cant see.  they're going to have to find your floater to break it up with laser.

[mits1]

I'm trying to figure out what could have caused the floater (and how to prevent more, even though the consensus is there's no way to do that).  In the morning I took a licorice root herbal remedy for the first time, then in a dimly lit elevator i saw a lightning streak at the side of my eye, and then after that i had a large black eye floater.  This sounds like a PVD, but was not detected by the doctors.  Is it possible that the vitreous can pull on the retina and create floaters, and then fall back in place? If the PVD is incomplete, am i still at increased risk for retinal tears? Also, even though the centre