Why do eyeglasses use a screw instead of a rivet?

[kayT]

@igor_frankensteen

You can move your eyes, but you wont be able to see in focus through the glasses when you do. The only place where the lenses are ground for close work, is in the center. The rest of the lens is either blank ground, or made for distance work.

@kayT

That does not appear to be true of my glasses.

@igor_frankensteen

Excellent. Who made the lenses please? I can’t even get any of the companies I’ve asked, to answer so much as a single question.

Walmart made the current pair (or at least sent them out to be made; I don’t know where); my optician made the previous two pairs.

[kayT]

@blood63

That must be an American thing. I live in Canada and have never seen a screw hold a lens in.

Just so you know, the screw just holds two parts of the frames together which, when the screw is removed, allows the lens to come out. Just in case you thought the screw was in the lens somehow.

[Weisshund]

@kayT

That does not appear to be true of my glasses.

I think you two are talking about 2 different lens types?

You say your glasses have the lens where they “softly” change to different powers.

I think he has actual old school bifocals that have no soft transition.
Moving the eyes with those is kind of weird, but they are great if you need a pair of glasses you can do like close tiny soldering work etc.
I was told i could not get anything of that extreme in the seamless lenses i think you might have?