reading while walking (3)

From Steven R. Fischer's A History of Reading:

The physical act of reading was anything but easy in the Middle Ages. This discouraged many.

Scribes often noted in the margins of their manuscripts the physical discomfort of reading and writing in dark, cold, draughty scriptoria. As one Florencio protested in the middle of the thirteenth century: "It is a painful task. It extinguishing the light from the eyes, it bends the back, it crushes the viscera and the ribs, it brings forth pain to the kidneys, and weariness to the whole body."

I hear you, Florencio.

What are examples of literary characters who got some kind of physical disability because of their excessive reading? Don Quixote doesn't count because it was the semantic content of the books he read what did him in. I'm thinking more among the lines of Clym Yeobright from Thomas Hardy's The Return of the Native, who ended up damaging his eyesight.

Also, are there accounts of members of a preliterate culture encountering for the first time a person engaged in reading? It must have seemed a puzzling and inscrutable activity...