Invented by Benjamin Franklin.

Bifocals have divided lenses for clearer distant and near vision. The top half of the lens is used to focus on things in the distance, such as across a room or across a street. The bottom half of the lens enables people to focus on things that are close, such as a book.

Having to constantly switch glasses depending on what he was trying to see aggravated Ben Franklin. So he cut the lenses of each pair of glasses in half and put a piece of each in a frame and thus, bifocals were invented.