For me, they didn't work out
I bought these to apply to a particular (expensive) pair of sunglasses - and that didn't work out.  The lenses curve quite a bit and I couldn't get a good seal.  If you don't get a good seal... well, at worst they fall off of course, but at best you get the blurriness that others have noted.  I suppose if I'd had glasses that were not wrap-around these would have worked as I'd hoped they would.
Rating: 3 stars