Bifocal Glasses and Their Technological Development
The American gentleman of science, Ben Franklin, who endured both nearsightedness as well as presbyopia, devised bifocal reading glasses in 1784 to obviate needing to frequently alternate between 2 sets of glasses.
The first lenses for rectifying astigmia were constructed by the British astronomer George Airy in 1825.
Along the history of bifocals, the building of spectacle frames also developed. Early on oculars were contrived to be either held in place with hand or by maintaining force on the nose. Girolamo Savonarola advised that oculars could be held in place with a ribbon passed over the subject’s head, this in turn fastened by the weight of a hat.
Entering modern bifocal history, the contemporary fashion of bifocal spectacles supported by temples passing over the ears, was produced in 1727 by the British lens maker Edward Scarlett. These designs were not at once prosperous, however, and assorted styles with attached handles like “scissors-glasses” and lorgnettes stayed fashionable throughout the eighteenth and into the early nineteenth century.
In the early twentieth century, Moritz von Rohr at Zeiss made the Zeiss Punktal spherical point-focus lens system which dominated the eyeglass lens domain for many years.
Despite the rising fame of contacts and laser restorative eye surgery, spectacles stay quite common, as their engineering has continued to evolve. For example, it’s currently possible to buy frames constituted of special memory metal alloys that return to their correct configuration after being bent. Other frames have spring-loaded hinges.
Glasses have come a long way, haven’t they? In fact, today you can even buy bifocal sunglasses.
Most of these designs are also distinctly better able to resist the stresses of day-to-day wear as well as the occasional accident. Modern frames are also frequently constructed from robust, light-weight materials like titanium alloys which weren’t obtainable in earlier times.
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