BIFOCAL LENS AND BIFOCAL SPECTACLES

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive bifocal lens and bifocal spectacles that eliminate a sense of incongruity in the use of a near zone and enable a definite selection of a region suited for the purpose of use.;SOLUTION: The bifocal spectacle lens consists of a single material having a uniform refractive index, and has a presbyopic lens zone 1B used for near vision in a part of a main lens zone 1A used for distant vision. When used, the presbyopic lens zone 1B as a whole is formed substantially into an arc or rectangle delimited by a substantially horizontal upper edge, a temporal side edge extending toward an ear in succession to the upper edge, and a lower edge conforming to a lower rim shape of a spectacle frame, and the upper edge and side edge form substantially straight boundary lines recognizable by the user.;COPYRIGHT: (C)2009,JPO&INPIT