Nowadays you still have to pay a lot for a pair of custom made glasses. How much would you pay for a pair of eyeglasses when these were first invented in the 13th century?
Certainly there was a lot of hand work involved while creating the lenses. Did this mean that only the extremely rich could afford glasses? Where there alternatives for the people without much money?
I’m at a loss for earlier periods, but between July and September 1384, there is record of 1,151 pairs of eyeglasses shipped to England, which suggests they weren’t a total extravagance. By the late 1400s, peddlers in Europe were selling eyeglasses in leather frames for 1 d. (denarius = pence/penny); for horn frames the cost was 9½ d. Though medieval price comparisons are notoriously vague, in 1490 a roof thatcher made 6 pence a day in England. As today, the real cost of eyeglasses lay in the frames, which could be wood (held on a stick), leather, metal, etc. In Venice, crystal lenses cost more than glass ones. See John Dreyfuss, “The Invention of Spectacles and the Advent of Printing, “ The Library 6th series, 10 (1988), 99. For leather v. horn see Glyn Walsh, “Spectacles through the Ages and Period Inaccuracies,” Optometry Today, Dec. 14, 2001, pp. 32-37.
Also, how did they calculate what glasses you should get and how precise was the manufacturing?
Also, when's the first depiction of someone wearing eyeglasses?
The earliest depiction of spectacles is Tommaso of Modena’s 1352 portrait of [Cardinal Hugh of St.-Cher reading] (http://www.historyofinformation.com/expanded.php?id=1755). I’m not sure how prescriptions were adjusted. From what I know, most lenses were magnifiers for reading rather than for nearsightedness. In intro to the early 15th-century Book of Margery Kempe, its clerical author recounts how he tried to use glasses to read a poorly written script (“he sett a peyr of spectacles on hys nose”) but that made it even harder to read.
As a follow up, what about Asia? Glass wasn't a common thing there as far as I know...