Current Bifocals and progressive lenses are static, in that the user has to change their eye position to look through the portion of the lens with the focal power corresponding to the distance of the object.
Bifocals, eyeglasses whose corrective lenses each contain regions with two distinct optical powers
Computer monitors are generally placed directly in front of users and can lead to muscle fatigue due to the unusual straight and constant movement of the head.
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A method for fusing the sections of the lenses together was developed by Louis de Wecker at the end of the 19th century and patented by Dr. John L. Borsch, Jr. in 1908
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Historians have produced some evidence to suggest that others may have preceded him in the invention; however, a correspondence between George Whatley and John Fenno, editor of The Gazette of the United States, suggested that Franklin had indeed invented bifocals, and perhaps 50 years earlier than had been originally thought.
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The diving beetle Thermonectus marmoratus has recently become notable when it was discovered that its aquatic larval stage has been found to have used in its principal eyes two retinas and two distinct focal planes that are substantially separated, in the manner of bifocals to switch their vision from up-close to distance, for easy and efficient capture of their prey, mostly mosquito larvae.
Bifocals |