Prior to the 13th century invention of eyeglasses, how did the many near-blind get along?

Well, a large majority of the population were engaged in agriculture, and probably managed all right at growing the crops, herding animals etc, when they knew the territory they lived in so well that everything was familiar to them. Those who were short sighted would do all right at things that required close work, like men would be able to do things like mending tools, sewing seeds, weeding, reaping, etc. women would be able to spin, sew, cook, do gardening, etc. Things would be more difficult for long sighted people, but as they would know their way around their local environment very well, they would probably be able to manage if they were careful.