Polarized lenses: What is this layer on the outside of the lens?

[steveadorjan]

I almost bought a pair of vintage (6-7 years' old BNIB, absolutely mint condition) Straight Jackets the other day, but I was put off by the visible edges of sth. like a thin film layer at the edges on the outside of the lenses. As far as I know, the AR coating is on the inner side of the lenses, not on the outside. On the other hand, Oakley's polarization technique is supposedly not a mere externally laminated filtering layer, but laminated in the lens material. So what exactly is this film layer?
I had grey polarized SJ lens a few years ago, which also had this layer (I sold the lenses immediately, as I only bought that pair for the frame). My main concern is durability (e.g. delamination, peeling of this layer).
Interestingly, on the only pair of polarized Oakleys I currently own (2016 Mainlink Ruby polarized), I don't see anything similar, so I wonder if something has changed with the newer models.

 

["TRUMP"]

Tinted lenses only have AR coating on the inside of the lens but lenses without tint(iridium) actually have an AR coating on the outside of the lens as well. Clear/transition/anything without a coating of iridium on the outside will have an AR coating on the outside (as well as the inside) to substitute for the iridium.

 

[steveadorjan]

Tinted lenses only have AR coating on the inside of the lens but lenses without tint(iridium) actually have an AR coating on the outside of the lens as well. Clear/transition/anything without a coating of iridium on the outside will have an AR coating on the outside (as well as the inside) to substitute for the iridium.

But the lenses I mentioned were Fire Iridium (polarized) and they still seemed to have the kind of film layer on the outside that my old Grey (polarized) lenses had.

OTOH, I've had multiple non-iridium (bronze, persimmon, yellow, grey etc.) that did not have this kind of visible film layer on the outside (they were not polarized lenses!).