When was the first bifocals invented

Our knowlege that he was involved in the supply of spectacles in his early adult life may cause us to consider that he may well have had the interest to experiment with bifocals at an earlier date. Yet the only portrait of Franklin in which he is depicted wearing bifocals is one by Charles Willson Peale, dated , when the old man was aged 81 and living once again in Pennsylvania.

This does at least suggest that we would be right to say that Franklin introduced bifocals to America. Wider public awareness of the invention only came about in the early s, following Franklin's death. During this period several authors published the Whatley letter, thereby cementing in the public mind the link between bifocals and Franklin.

Peale, having painted Franklin wearing bifocals, is known to have made his own pair in and may have been responsible for introducing the concept to the first US optician, John McAllister, some time after The idea for bifocal spectacles, attributed by some people to Franklin in both Britain and the US, though never patented by him or anyone else soon led to further developments.

The use of hinged supplementary visors to hold reading lenses was patented in London by John Richardson in By Isaac Schnaitman, a German immigrant to Philadelphia, had taken out a patent on one-piece lenses with both distance and reading portions ground on to one piece of glass. Another claimant to the title? Benjamin West , an American artist, originally from Philadelphia, was a natural friend for Franklin in London. He would later become President of the Royal Academy from West is known to have been an early wearer of 'divided glasses' or bifocals, possibly before , but probably not before Franklin.

That has not stopped historians pushing the claim of West or his predecessor at the Royal Academy, Sir Joshua Reynolds, to have 'invented' bifocals in the s. Reynolds was a personal friend who often visited Franklin in Craven Street, so he would have seen Franklin using bifocals if, indeed, he had been doing so.

Historical images of Reynolds show him using only single vision lenses. Bifocals are referred to as eye-glasses which have two dissimilar optical powers. These are generally prescribed to the people who have the syndrome of presbyopia. While the advantages are many, there ought to be some disadvantages as well.

These lenses can lead to a headache and wooziness of the users which happens due to the quick switch of vision from the upper lenses to the lower lenses. Adjustment of the lower very often is needed and the use of computers and mobile screens also cause the power to exfoliate. Overall it can be referred to as a great invention by Sir Benjamin Franklin to the world. Who Invented Bifocal Glasses.

An advantage of round seg bifocals is that the line separating the distance and near zones of the lens tends to be less noticeable than the upper line of a D-seg bifocal.

But the optical center of the near zone of a round seg bifocal is lower in the lens, which can be bothersome to some wearers. While bifocals work great for tasks like driving and reading, they are limited in their ability to provide clear vision at points in between, such as the distance to a computer monitor. Trifocal eyeglass lenses have an additional ribbon-shaped lens segment immediately above the near seg for seeing objects in the intermediate zone of vision — approximately 18 to 24 inches away.

Flat-top trifocal lens. Executive trifocal lens. This intermediate segment provides 50 percent of the added magnifying power of the near seg, making it perfect for computer use and for seeing your speedometer and other dashboard gauges when driving. Trifocals are especially helpful for presbyopes over age 50, who have less depth of focus than younger presbyopes, who may still be able to see objects at arm's length reasonably well through the top part of their bifocals.

As with bifocals, the most popular trifocals have a flat-top FT design, with the near and intermediate segments being 28 mm wide.

Some people are reluctant to try trifocals because they are concerned about the appearance of the lenses or are worried that trifocals will be difficult to get used to, since the top line of the intermediate zone is close to the center of the lens. But in fact, most people who try trifocals are very pleased with the added range of vision they provide compared with bifocals and the wide field of view they offer for computer use.

Although most bifocals and trifocals have visible lines at the border of lens segments, there is a blended round-seg bifocal that has a less noticeable near segment than its regular round-seg cousin. Blended bifocal lens. With no visible lines, a blended round seg bifocal offers a more youthful appearance than lined bifocals and trifocals. But a drawback of the blended bifocal is that the optics of the lens are slightly distorted at the blended border between distance and near zones.

This may be bothersome to some wearers. The word "bifocals" was created at the same time as the word "trifocals". John Isaac Hawkins invented trifocals, glasses meant to focus on three different distances, in Though he gave the glasses their name, he credited Benjamin Franklin for inventing the bifocals. For many years, bifocals were the same style as Dr.

The rim for each eye contained two pieces of glass, which made them fragile. Fusing the lenses together made them stronger.