Ah, yes. The do-it-yourself slit lamp test.
My eye doc can see the large floaters in both of my eyes, which technically are Weiss rings caused by vitreous detachment around the optic nerve. The ring has collapsed into more of a pancake shape, which is typical for these kinds of floaters, and looks like a large grey cloud with a dark grey outline. Some days, it really bugs me.
Two important things to consider about floaters before chasing down supplements or toxins or what have you:
1) Do you have astigmatism? Folks of all ages with astigmatism tend to be prone to floaters. I've had severe astigmatism since childhood, and floaters have been a part of my life as long as I can remember.
2) Floater frequency will increase with age. And the combination of advancing age with astigmatism will set you up for floaters, especially the Weiss ring vitreous detachment floater, guaranteed. So if you're older than 40, you might not be able to do much about them.