I wear bifocal "photogray" glasses.For me they work fine.Even now with heavy snow and bright sunshine
they get dark enough to be comfortable.
However when you go back inside they take a minute to lighten up.I just look over the top or take them
while I get out of the winter coats, heavy sweaters, long johns,heavy gloves,snow boots,earwarmers,
do the big snotblow,-did I get that all?
Also:The halfmoons donot darken completely.
I was told Polarized- plastic lenses
Photo gray-Glass lenses. They are abit heavier.I get them hardened or tempered
whatever it's called.
When inside they are a 'tetch' darker than clear glasses.
They are relatively scratchproof.
In the summer I always wear them on an idiot string.
I hope this helps a bit.


Anton V.