I am wondering if back before glasses how did those who are farsighted read and write. Also, how did nearsighted people see things at a distance. Were there techniques or technology that solved these issues. To me it seems like a large issue.
On a side note, I also wonder if these people with vision impairment would be considered mentally disabled back then? Just a thought.
Keep in mind that the amount of (especially) nearsighted people is a very modern problem. While myopia is a hereditary trait, it's rapid spread has to be based on environmental factors. Studies in Singapore, South Korea and Taiwan (i.E. highly developed countries) showed that as many as 80-90% of 18-year-olds are nearsighted - while in the early 50s, myopia was nearly nonexistent and in 1970, only about 30% of young adults were nearsighted. This rapid growth can not be attributed to hereditary spread alone. Commonly, acts such as reading, working on electronic devices etc are given as environmental factors - in short: Everything that is about focusing your view on something close to you helps building myopia.
Now, the further we go back in time, the less of these actions you will encounter. People and especially kids spent more time outdoors doing tasks that needed the view to be focused farther away, (I have also found articles claiming sunlight to be a factor as it supposedly leads to the retina producing a chemical that influences the growth of the eye) thus leading to a "normal" development of the eyes and to myopia being a very rare thing.