bifocal lens
Quick Summary
A bifocal lens is a type of eyeglass lens that corrects for both near and distant vision. Invented by Benjamin Franklin in 1784, bifocals have two distinct parts, each with a different focal length. This allows the wearer to see clearly at both far and close distances without needing to switch glasses. The design has evolved over time, with various types like cemented, fused, and one-piece bifocals being developed. Bifocal lenses are a significant advancement in vision correction, helping many people overcome common vision impairments like farsightedness and nearsightedness.
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