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.
Once the most popular style of bifocal, the lined bifocal has taken a back seat to an advanced lens design, the progressive addition lens or PAL. Also called a âno-line bifocal,â this type has multiple strengths in one lens that change gradually as the user moves her eye down to the bottom of the lens.