Subject: I have polarized presciption sunglasses. How are they made?

I think this question has less to do with chemistry than with physics,which I
don't know much about. My polarized sunglass lenses are glass. I was wondering
how glasses are polarized, I was thinking that they might be a coated with
something.I have two reasons for this. Once I was handling some glass lensed
polarised sunglasses offered for sale and was told to only touch the lenses with
a "special cloth" also for sale.My second reason is that I think that the
structure of optical glass would not be destroyed if treated too much.   
please tell me whether it is something done to the glass, or if it is something
painted on the glass. Please tell me how this works.

Re: I have polarized presciption sunglasses. How are they made?