subject: The History Of Progressive Reading Glasses [print this page] Also called no line bifocals, progressive reading glasses have long been enjoyed by the needed. Those regular users of progressive eyeglasses have certainly known the benefits they can get. For instance, progressive spectacles never cause image jump, which happens frequently to bifocal or trifocal eyeglass wearers. Since progressive eyeglasses use lenses with a gradient of increasing lens power, a significantly smoother power transition will be offered. It is reasonable to claim that those no line bifocal reading glasses have made a noticeable improvement, compared with those traditional bifocal reading glasses. Most historians or scientists have reached an acknowledgement that the first pair of bifocal spectacles was created by Benjamin Franklin in around 1784. However, few people know the exact origin of the progressive addition lenses.
In 1907, Own Aves was granted with a British patent for a PAL, which was considered as the emergence of progressive addition lenses. This initial version of progressive lenses included progressive lens design as well as manufacturing process. The power gradient of Aves progressive lenses was achieved by making a conical back surface and a cylindrical front with opposing axes. This was considerably different from the modern design. It was a pity that this design never gained commercialization. And progressive reading glasses were not available at that time.
The first commercialized PAL product was proven to be developed in 1922 by Duke Elder, marketed by Gowlland of Montreal as Ultrifo. These lenses took use of an arrangement of aspheric surfaces. In fact, the first PAL of modern design was developed only by 1953, under the name of Varilux lenses. After more than a half centurys progression, progressive power lenses in the modern time are more sophisticated and have gained greater patient acceptance. There have been also many forms of progressive reading glasses offering customized designs for special groups of patients. Most of the manufacturers now use computer controlled machines to cut and polish the surface of progressive lenses.
C: Progressive reading glasses were available to the pubic at a time much later than that of bifocal reading glasses. However, modern progressive addition lenses are quite sophisticated and have gained greater patient acceptance.
