It's amazing to watch the skill involved in making those. There is no skill anymore, all done by machines and the lenses are ground completely by machine too, just push a button. When I started making specs in 1993 it was so much more interesting, still used machines but they were not all automated like they are now.
I worked with an old gent who worked right up till his mid 80's in an optical lab, it's all he had ever done since his first job of scraping the left over flesh off the inside of tortoise shells and marking/cutting the clearest bits out, sadly no longer with us.
The only thing needed by modern techs is a finger to push the button and a phone to call the engineer when the machine goes down!