I'll try to dig up a link to my previous answer to this, basically it boils down to a few things:

First, research seems to indicate that people who spend very little time outside are more likely to develop myopia, so the incidence of myopia is much higher today than it would have been in pre-industrial times.

Second, visual acuity below 20/20 vision doesn't impact a pre-industrial and especially pre-literate lifestyle as much as one might imagine. There's no need to read road signs in the distance, for example. The vision requirements to be successful day to day for most jobs are not that stringent. Having modestly degraded vision would only exclude you from a very small subset of possible jobs (say, archer).

Third, people with the worst eyesight who would be effectively blind (unable to do any productive work, for example) would be forced to depend on their family or community for support, and we know that this sort of thing happened often enough to give rise to tropes such as the blind beggar.

In short, most folks who wear glasses today would have been able to live full and productive lives, only a small percentage of people with extremely bad eyesight would be seriously negatively impacted but they would likely be forced to live a life of dependence on others.

Just to add another question, how were glasses discovered? How did people figure out that using glass would fix your eyesight? And how accessible were glasses? Could a farmer get a pair?

Here are some previous threads on this topic: https://www.reddit.com/r/AskHistorians/wiki/health#wiki_eyesight.2C_glasses.2C_and_contact_lenses