Most hunter-gatherer societies would accomodate the elderly and the incapacitated to some extent, and near sightedness would certainly had qualified. This doen't mean the nearsighted individual would have been maintained in idleness, he would have occupied himself to the best of his abilities in contributing to the well being of all. This could have been done through a host of other activities such as gathering, fishing (with a net for instance) and producing stone tools and ceramics.