Hi, Nobody knows exactly when spectacles were intended. It is very clear that they were invented between 1280 and 1300 A.D.
They were invented in 1286
The reason for putting prism in spectacles is to reduce diplopia (double vision) in people who have strabismus (a muscle imbalance that prevents them from maintaining fixation on an object). In cases...
no one knows who invented the spactales...they date back as a simple mag. glass in 4 BC