| 摘要 |
Bifocal contact and intraocular lenses are described wherein a viewing area which has an extend generally corresponding to the maximum pupil area of the wearer, said viewing area having a central circular refractive zone having a first focal length corresponding to distance or reading vision, and a plurality of annular, concentric refractive zones which alternate between a second focal length corresponding to the other of reading and distance vision and said first focal length as they extend outwardly from said central zone, wherein the total number of said zones is at least 20. Preferably, at least one of the zones has a power which is more negative than a zone of the same character which is situated closer to the center of the lens. |
