Encyclopedia > Bifocals

  Article Content

Bifocals

Bifocals are eyeglasses that have two sets of corrective lenses for people with impaired vision for both close and long distance viewing.

This form of corrective lens set was invented by Benjamin Franklin who needed two sets of glasses to deal with each aspect of the above kind of impaired vision.

This proved cumbersome, but the solution presented itself when he realized that when a person views something at close range, they usually look down and the reverse is true when they view at a distance. Taking advantage of that fact, he designed bifocals with the lenses for close viewing in the lower half of the frame and the distance viewing lenses on the upper.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Canadian Music Hall of Fame

... Cohen 1992 Ian and Sylvia[?] 1993 Anne Murray 1994 Rush 1995 Buffy Sainte-Marie[?] 1996 David Clayton-Thomas[?] 1996 Denny Doherty[?] 1996 John Kay[?] ...

 
 
 
This page was created in 37.7 ms