Retired ophthalmologist David Fleishman created an amazing site about "Eyeglasses Through the Ages." From his introduction:
We generally take for granted one of the world’s most important inventions--spectacles. Imagine what life would be like not being able to see images clearly or sharply. According to a January 11, 1999 feature article in Newsweek Magazine , reading glasses are one of the most important inventions of the past 2000 years. They developed because of the work of artisans, like glassmakers, jewelers and clockmakers, along with some of the most brilliant scientific minds over the centuries. According to Dr. J. William Rosenthal, "Philosophers, monks, mathematicians, physicists, microscopists, astronomers, and chemists all played vital roles in developing this instrument."Link (via MAKE:)
No one really knows about the early history of image magnification. In ancient times, someone noticed that convex-shaped glass magnified images. Sometime between the year 1000 and 1250 crude technology began to develop regarding reading stones (simple magnifiers). English Franciscan Friar Roger Bacon (1220 -1292), in his 1268 ‘Opus Majus’, noted that letters could be seen better and larger when viewed through less than half a sphere of glass. Bacon's experiments confirmed the principle of the convex (converging) lens, described by Alhazen (965-1038) Arabian mathematician, optician and astronomer at Cairo, and even earlier by the Greeks. Bacon recognized that this could assist weak eyes or the vision of aged persons.
Early recorded evidence demonstrates that glasses first appeared in Pisa, Italy about the year 1286. Technically, they were formed from two primitive convex shaped glass/crystal stones. Each was surrounded by a frame and given a handle. These were then connected together through the ends of their handles by a rivet.