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Year Invented - 1784
Inventor - Benjamin Franklin (American polymath and founding father).
Function - The word "bifocal" literally means "two focuses," as the lens powers are split in half to help people see clearly at two different distances.
Details - The upper part of the lens corrects distance vision, while the lower part corrects near vision. There are common types: D-shaped (medium lower oval), segmented (50/50 lens split), and round (tiny lower circle).
Visual representation of D-shaped/round bifocals (most common type).
Photo Creds: Oscar Wylee
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