E-commerce is a major factor in the U.S. economy because it assists companies with many levels of current business transactions, as well as creating new online business opportunities that are global in nature.
Eye Health. A bifocal is a lens that has two focal points, usually one lens for viewing distant objects, and one lens for viewing close objects. A bifocal is also known as a multi-focal lens. Ben Franklin is credited as the inventor of the original bifocal lens. Presbyopia.
Photo Credit UberImages/iStock/Getty Images. Bifocal lenses take some adjustment for many people, whether you start with bifocals or switch from regular lenses. New bifocal wearers might experience difficulty as they move from looking through the top to the bottom of the lenses.