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.
They minimize or eliminate the need for reading glasses after surgery. Conventional monofocal lenses only correct for distance vision, meaning reading glasses are still needed after surgery. Multifocal IOLs (Intraocular Lens) can be an option in some patients to help improve both distance and near vision. Toric implants are available to correct astigmatism. A lens for better color vision is in development (shown here next to a dime).