irving rips created the first seamless bifocal a precursor to all progressive lenses.
who created the first seamless bifocal a precursor to all progressive lenses?
irving rips
since many inventions are developed independently by more than one person, it is possible that the invention of bifocals may have been such a case.









































john isaac hawkins, the inventor of trifocal lenses, coined the term "bifocals" in 1824 and credited franklin. 









































in 1955, irving rips of younger optics created the first seamless or "invisible" bifocal, a precursor to all progressive lenses. this followed howard d. beach's 1946 work in "blended lenses", o'conner's "ultex" lens in 1910, and isaac schnaitmann's single-piece bifocal lens in 1837. 









































section::::history.:construction.
bifocals
bullet::::- for those new to progressive lenses, an accommodation period is often required because the brain needs to learn to adapt to them. this period varies from a few hours for some individuals up to around two weeks. during this period, side effects can include headache and dizziness. it is advised that, when these symptoms set in, the progressive lenses be removed for a short period and replaced after symptoms have subsided. returning to an older prescription or different type of lens design (bifocal, trifocal) only serves to increase the adaptation period to the progressive lenses. some wearers find the visual discomfort caused by these distortions outweigh the benefits of wearing pals; this is known as progressive non-tolerance. however, manufacturers claim acceptance rates of 90%–98%.
progressive lens