As early as 700 BC, the Assyrians used polished crystal to magnify objects. Ancient Egypt and Babylon used similar objects and the ancient Romans and Greeks filled glass spheres with water for the same purpose. Seneca, the Roman philosopher, wrote about filling transparent vessels with water in order to magnify objects seen through them. Emperor Nero, who reigned during Seneca’s lifetime, is said to have used the first monocle, an emerald held in front of one eye as a lens to better see at distances.
Sometime between the 11th and 13th centuries, monks used reading stones to help them see the manuscripts they were illuminating. These reading stones were made by cutting glass spheres in half and holding them over the text or artwork needing magnification.
Roger Bacon, the forerunner of modern science, wrote of the magnification properties of lenses in 1262. His observations, based on experiments, were used by later scientists in the burgeoning studies of the natural sciences.
In conjunction with the Age of Enlightenment, during which new ideas about scientific subjects like earth sciences and astronomy were developed, optics became an important topic. Italian Salvino D’Armate of Florence is credited with inventing the first pair of wearable eyeglasses in 1284. It is said a memorial once stood, honoring him, but it no longer exists. Others, like Alessandro di Spina, were also given credit for the first eyeglasses, and though doubt exists as to the actual inventor, all prototypes were probably invented in Italy late in the thirteenth century. The use of eyeglasses was depicted in several artworks created in the fourteenth and fifteenth centuries, giving credence to the existence of spectacles during this period.
Hyperopia, or farsightedness, and presbyopia, the vision problem that develops with age, were the first eye conditions for which glasses were invented. These armless convex-lensed glasses, called pince-nez, were pinched together to sit on the bridge of the nose. Over the years, various contraptions were used to hold the lenses, from a ribbon attached to the lenses and wrapped around the wearer’s head to lorgnettes that held the lenses atop a long handle. Others with attached handles that operated like scissors were called scissors-glasses. Edward Scarlett of Great Britain invented the first earpieces similar to what are used today.
Lenses for nearsightedness, or myopia, weren’t discovered until later, when Nicholas of Cusa is credited with using concave lenses for this condition. In his 1604 paper on optics and astronomy, German astronomer Johannes Kepler offered a scientifically correct explanation of the effectiveness of concave and convex lenses to correct vision deficits. His treatise formed the basis of today’s optical science.
In 1784, almost two centuries after Kepler’s writing, Benjamin Franklin invented the first pair of bifocals. Reportedly suffering from both myopia and presbyopia, Franklin was attempting to avoid the aggravation of switching between pairs of glasses to read or to see distant objects. His invention had a frame that held two lens sections together. The idea of cementing these two lenses together was not conceived for another one hundred years.
Since then, the technology for eyeglass lenses and frames has improved, contact lenses have been developed, and lasers are used to correct some vision problems. What was a tremendous mystery centuries ago is now an ordinary part of most people’s lives.