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.
The upper portion of the glasses contains distance (minus) lenses and the lower portion contains reading (plus) lenses. We do not recommend bifocals because the child is likely to use the distance lenses in the upper half of the glasses for close work, thereby further elongating the eye and causing irreversible myopia.