Progressive lenses, or no line bifocals, are commonly prescribed to people over forty who need help to correct the gradual loss of clarity, or Presbyopia.
Progressive lenses provide a smooth transition from distance, through intermediate, to reading correction. Rather than two distinct zones like old-fashioned bifocals, the progressive lenses gradually change powers to offer you the best in vison correction.

Progressives help ease eye strain and provide a more natural vision correction. No need to carry two pairs of glasses and no more unattractive lines across your lens.
A Progressive or Bifocal prescription will have a power or sphere value as well as an Add power noted.