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.
Occupational multifocal lenses can be achieved by simply positioning common multifocal lenses in unusual ways. Ordinary trifocal lenses are properly fitted by placing the top line to be just below the pupil. By placing trifocal lenses higher, the wearer is needless to look down or tilt back the head to get near vision.