That’s how it would work in a post apocalypse too. People who wear glasses right now are typically on vision plans that allow for a new pair every year. I have like 5 old pairs, 4 of which no longer are really strong enough.

So depending on how far down the road post apocalypse you either randomly go through houses until you find a pair good enough, or if enough time has passed there will almost certainly be people specializing in selling glasses and medical things.

Now if you are far sighted all you have to do is walk into any abandoned CVS and go look through the huge rack of cheater lenses they have.