It wasn't long after we figured out that lenses could be used for correcting vision that we also realized they could be used for spying. The first monocular telescope was invented in 1603, and soon, respectable folks were buying them to better see details on the stage at the opera—not at all to discreetly examine the opposite sex.
These tiny telescopes, called lorgnettes (derived from the word "to leer or stare") in French, came attached to a long handle, and were often ornately decorated. As spectacles were seen as an indication of infirmity or old age, no high-society lady wanted to be seen in them. Lorgnettes were more like fine jewelry, and only put near the face when one wanted to observe an element of an opera or play more closely.
As technology evolved, so did lorgnettes. In the 18th century, aristocratic men took to wearing the single-lens monocle, while the ladies tried all sorts of dual-lens of contraptions, including hand fans with lenses built into them, and "scissors-glasses." These peculiar spectacles have stems attached to each lens that come together under the nose at a handle.
An Englishman named George Adams first thought to attach the lenses to each other and then a long handle on one side, saving ladies from having the handle right under their noses. These became what we now think of as lorgnettes, again intricately decorated and encrusted with fine jewels for the wealthy society set.
At the end of the 19th century, binocular technology finally improved enough to allow viewers to focus both eyes on the same point. Like lorgnettes, binoculars were soon attached to long handles, and these handled contraptions evolved into the ornate opera glasses we know today.