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.
These are two of the different types of concentric bifocal pattern lenses for bifocal and multifocal lenses. The main vision disorder that multifocal and bifocal lenses are used for is presbyopia â a condition that happens as we age that affects our ability to focus on objects that are near.